diagnostic methods

SECTION 2Diagnostic Methods

ContentsDiagnostic Methods..........................................................................2-1

Overview.......................................................................................2-1

Diagnostic Tools...............................................................................2-2

Scan Tool Setup and Functionality..................................................2-3

Vehicle Check/Preparation...............................................................2-4

Visual Checks...............................................................................2-4

Vehicle Preparation ......................................................................2-4

Quick Test Description.....................................................................2-5

Clear the Continuous Diagnostic Trouble Codes (DTCs)and Reset the Emission Monitors Information in thePowertrain Control Module (PCM) ..............................................2-7

Resetting The Keep Alive Memory (KAM) ......................................2-8On-Board System Readiness (OSR) Test.......................................2-9Output State Control (OSC)...........................................................2-10Output Test Mode (OTM)...............................................................2-11Parameter Identification (PID)........................................................2-12Freeze Frame Data........................................................................2-20

2008 Powertrain Control/Emissions Diagnosis, 8/2007

SECTION 2Diagnostic Methods

Contents (Continued)Flash Electrically Erasable Programmable Read Only

Memory (EEPROM)...................................................................2-22Diagnostic Monitoring Test Results Mode 6.............................2-24

On Board Diagnostic (OBD) Drive Cycle ......................................2-25Intermittent Diagnostic Techniques................................................2-28

Recreating the Fault ...................................................................2-28

Accumulating PCM Data ............................................................2-28

Comparing PCM Data ................................................................2-29

Adaptive Fuel Diagnostic Trouble Code (DTC) DiagnosticTechniques ................................................................................2-30


Diagnostic Methods 2-1

Diagnostic Methods

Overview

The Diagnostic Methods Section provides information on routine diagnostic tasks.

When following powertrain diagnostics on vehicles with on board diagnostics (OBD), the systemmay be checked by an off-board tester referred to as a scan tool. This section contains informationfor carrying out diagnostics with a scan tool. A scan tool has certain generic capabilities that arestandard across the automotive industry in the United States and Canada. All functions areselected from a menu. Refer to the instruction manual provided by the tool manufacturer.


2-2 Diagnostic Methods

Diagnostic Tools

Below is an equipment list with corresponding part numbers:

REQUIRED EQUIPMENT: Vehicle Communication Module (VCM) and Integrated Diagnostic System (IDS) software with

appropriate hardware, or equivalent scan tool with functionality described under Scan Tool Setupand Functionality.

Rotunda Smoke Machine, Fuel Evaporative Emission System Tester 218-00001 (522) orequivalent.

RECOMMENDED EQUIPMENT: Rotunda Vacuum/Pressure Tester 164-R0253 or equivalent. Range 0-101.3 kPa (0-30 in-Hg.)

Resolution 3.4 kPa (1 in-Hg.) Rotunda Vacuum Tester 014-R1054 or equivalent. Range 0-101.3 kPa (0-30 in-Hg.) Rotunda 73III Automotive Meter 105-R0057 or equivalent. Input impedance 10 Megaohm

minimum.

Spark Tester D81P-6666-A (303-D037) or equivalent. Non-powered test lamp.

OPTIONAL EQUIPMENT: Rotunda Fuel (Gasoline) pressure test kit 134-R0087 or equivalent. (Use tool manufacturers

instructions.)



Scan Tool Setup and Functionality

Connect the scan tool to the data link connector (DLC) for communication with the vehicle.The DLC is located in the driver side compartment under the steering column. It is attached to theinstrument panel and accessible from the driver seat.

The DLC is rectangular in design and capable of accommodating up to 16 terminals. Theconnector has keying features to allow easy connection.

The required scan tool functions are described below: monitor, record, and playback of parameter identification (PIDs) freeze frame PID data diagnostic test modes; self-test, clear diagnostic trouble codes (DTCs) output test mode resetting keep alive memory (KAM) diagnostic monitoring test results (mode 6) for on board diagnostic (OBD) on board monitors on-board system readiness (OBD monitor completion status)Some of these functions are described in this section. Refer to the scan tool manufacturersinstruction manual for specific information on scan tool setup and operation.

International Standards Organization (ISO) 14229 Diagnostic Trouble Code (DTC)Descriptions

The ISO 14229 DTC is a set of common requirements for diagnostic systems. The scan tooldisplays a failure type and a status type with the DTC. The types display additional information onthe scan tool for the condition that set the DTC. For a list of failure type descriptions, refer toSection 1, Powertrain Control Software, International Standards Organization (ISO) 14229Diagnostic Trouble Code (DTC) Descriptions.



Vehicle Check/Preparation

Before using the scan tool to carry out any test, refer to the important Safety Notice located at thebeginning of this manual and the necessary visual checks listed below.

Visual Checks Inspect the air cleaner and inlet duct. Check all engine vacuum hoses for damage, leaks, cracks, kinks, and proper routing. Check the electronic engine control (EEC) system wiring harness for proper connections, bent or

broken pins, corrosion, loose wires, and proper routing. Check the powertrain control module (PCM), sensors, and actuators for physical damage. Check the engine coolant for proper level and mixture. Check the transmission fluid level and quality. Make all necessary repairs before continuing with the quick test. Refer to Section 3, Quick Test.

Vehicle Preparation Carry out all safety steps required to start and run vehicle tests. Apply the parking brake, place

the gear selector lever firmly into the PARK position on automatic transmission vehicles orNEUTRAL on manual transmission vehicles, and block the drive wheels.

Turn off all electrical loads such as radios, lamps, A/C, blower, and fans. Start the engine (if the engine runs) and bring it up to the normal operating temperature before

running the quick test.



Quick Test Description

Quick Test

The quick test is divided into 3 specialized tests:(1) Key On Engine Off (KOEO) On-Demand Self-Test(2) Key On Engine Running (KOER) On-Demand Self-Test(3) Continuous Memory Self-TestThe quick test checks the integrity and function of the electronic engine control (EEC) system andoutputs the test results when requested by the scan tool. The quick test also provides a quickcheck of the powertrain control system, and is usually carried out at the start of each diagnosticprocedure with all accessories off. The quick test is also carried out at the end of most pinpointtests for verification of the repair and to make sure no other concerns are incurred while repairinga previous concern. A system pass is displayed when no diagnostic trouble codes (DTCs) areoutput and a scan tool communication error does not exist. System pass means that hardwaremonitored by the powertrain control module (PCM) is functioning within the normal operating limits.Only a system pass, a DTC, or an incomplete on board diagnostic (OBD) drive cycle (P1000) isdisplayed.

For applications that use a stand-alone transmission control module (TCM) the PCM does notoutput TCM DTCs. For TCM self-test and diagnostics, refer to the Workshop Manual Section307-01 Automatic Transmission.

Key On Engine Off (KOEO) On-Demand Self-TestThe KOEO on-demand self-test is a functional test of the PCM carried out on-demand with the keyon and the engine off. This test carries out checks on certain sensor and actuator circuits. Aconcern must be present at the time of testing for the KOEO self-test to detect the concern. Whena concern is detected, a DTC is output on the data link at the end of the test as requested by thescan tool.

Key On Engine Running (KOER) On-Demand Self-TestThe KOER on-demand self-test is a functional test of the PCM carried out on-demand with the keyon, the engine running and the vehicle stopped. A check of certain inputs and outputs is madeduring operating conditions and at a normal operating temperature. The brake pedal position,transmission control, and the power steering tests are part of the KOER on-demand self-test andmust be carried out during this operation if applicable. These are described below. A concern mustbe present at the time of testing for the KOER on-demand self-test to detect the concern. When aconcern is detected, a DTC is output on the data link at the end of the test as requested by thescan tool.

Brake Pedal Position (BPP) TestThe BPP test checks the ability of the EEC system to detect a change of state in the BPP switch.The brake pedal is briefly applied and released on all vehicles equipped with a BPP input. This isdone during a KOER on-demand self-test.



Quick Test Description

Power Steering Pressure (PSP) TestThe PSP test checks the ability of the EEC system to detect a change in the power steeringsystem fluid pressure. The steering wheel is briefly turned at least 1/4 of a revolution on vehiclesequipped with a PSP switch or sensor. This is done during a KOER on-demand self-test.

Transmission Control Switch (TCS) TestThe TCS test checks the ability of the EEC system to detect a change of state in the TCS. Theswitch is briefly cycled on all vehicles equipped with a TCS input. This is done during a KOERon-demand self-test.

Continuous Memory Self-Test

The continuous memory self-test is a functional test of the PCM carried out under any condition(engine running or off) with the key on. Unlike the KOEO and KOER self-tests, which can only beactivated on-demand, the continuous self-test is always active. A concern does not need to bepresent when accessing continuous memory self-test DTCs, making the test valuable whendiagnosing intermittent concerns. The vehicle may need to be driven or the on board diagnostic(OBD) drive cycle completed to allow the PCM to detect a concern. Refer to On Board Diagnostic(OBD) Drive Cycle in this section for more information. When a concern is stored in memory, aDTC is output on the data link when requested by the scan tool.

There are two types of continuous DTCs. The first type is an emission-related code whichilluminates the malfunction indicator lamp (MIL) in the instrument cluster. The second is anon-emission related, non-MIL code which does not illuminate the cluster indicator.

For emission-related MIL codes, the PCM stores the DTC in continuous memory when a concernis detected for the first time. At this point the DTC does not illuminate the MIL and is nowconsidered a pending code. The purpose of pending codes is to assist in repair verification byreporting a pending DTC after one drive cycle. If the same concern is detected after the nextignition start-run cycle, the emission-related MIL code illuminates the MIL. The MIL remains oneven if the concern is intermittent. The MIL is extinguished if the concern is not present through 3consecutive drive cycles or if the concern is fixed and the DTCs are cleared. Also, anemission-related pending MIL and any non-emission related, non-MIL DTCs are erased afterapproximately 40 vehicle warm-up cycles or if the DTCs are cleared.

Any scan tool that meets OBD requirements can access the continuous memory to retrieveemission-related MIL DTCs. However, not all scan tools access pending and non-emission related,non-MIL DTCs in the same way.

During most diagnostic procedures in this manual, it is required that all DTCs be retrieved andcleared. Consult the instruction manual from the tool manufacturer for specific instructions.



Clear the Continuous Diagnostic Trouble Codes (DTCs) andReset the Emission Monitors Information in the Powertrain

Control Module (PCM)

Description

All on board diagnostics (OBD) scan tools support the clearing of continuous DTCs and resettingof emission monitors information in the PCM.

The clearing of the continuous DTCs allows the scan tool to command the PCM to clear/reset allemission-related diagnostic information. While carrying out this operation DTC P1000 is stored inthe PCM until all the OBD system monitors or components have been tested to satisfy a drivecycle without any other concerns occurring. For more information about a drive cycle, refer to OnBoard Diagnostic (OBD) Drive Cycle in this section.The following events occur when the continuous DTCs and the emission monitors information iscleared from the PCM: the number of DTCs is reset the DTCs are cleared the freeze frame data is cleared the diagnostic monitoring test results are reset the status of the OBD system monitors is reset DTC P1000 is set



Resetting The Keep Alive Memory (KAM)

Description

Resetting the KAM returns the powertrain control module (PCM) memory to its default setting.Adaptive learning contents such as adaptive airflow, idle speed, refueling event, and fuel trim areincluded. Clear the continuous diagnostic trouble codes (DTCs) in the PCM and reset the emissionmonitors information, is part of a KAM reset. Refer to Clear the Continuous Diagnostic TroubleCodes (DTCs) and Reset the Emission Monitors Information in the Powertrain Control Module(PCM) in this section. Both can be useful in post-repair testing.After the KAM has been reset, the vehicle may exhibit certain driveability concerns. It is necessaryto allow the engine to idle at normal operating temperature with the air conditioning (A/C) OFF for2 minutes. Then drive the vehicle to allow the PCM to learn the values for optimum driveability andperformance.

This function may not be supported by all scan tools. Refer to the scan tool manufacturersinstruction manual.

If an error message is received or the scan tool does not support this function, disconnecting thebattery ground cable for a minimum of 5 minutes may be used as an alternative procedure.



On-Board System Readiness (OSR) Test

Description

All on board diagnostic (OBD) scan tools display the on-board system readiness (OSR) test. TheOSR displays the supported monitors on the vehicle and the status of all monitors (complete or notcomplete) at that time. Fuel, misfire, and comprehensive component monitors (CCMs) runcontinuously and always display YES status. Clearing the continuous diagnostic trouble codes(DTCs) and resetting the emission monitors information in the powertrain control module (PCM), orresetting the keep alive memory (KAM) causes the non-continuous monitors to change to a NOstatus.

A detailed description of completing the OBD monitors is found in this section. Refer to On BoardDiagnostic (OBD) Drive Cycle in this section.



Output State Control (OSC)

Description

WARNING: Safety must be observed when using OSC. Failure to follow theseinstructions may result in personal injury.The OSC aids in diagnosing output actuators associated with the powertrain control module (PCM)for the engine. This mode allows the technician to command the individual actuator state. Forexample: the output can be enabled or disabled, the duty cycle or the angle of the output can beincreased or decreased. The OSC is used to help test the electrical, hydraulic or mechanicalcomponents of the vehicle. This function is supported by the vehicle strategy but may not bepresent on all vehicles or available on all scan tools.

Retrieve the continuous codes and carry out a key on, engine off (KOEO) and key on, enginerunning (KOER) on-demand self-test before using any OSC. Any diagnostic trouble codes (DTCs)related to the transmission range (TR) sensor, output shaft sensor (OSS) or the vehicle speedsensor (VSS) must be fixed or the PCM does not allow the OSC to operate.The OSC has 2 options for operation, the Bench Mode and the Drive Mode. The Bench Mode isfunctional only when the vehicle gear selector is in the PARK or NEUTRAL position. The BenchMode may be used when the engine is on (running) or off (not running).Each OSC function has a unique set of vehicle operating requirements that the technician isrequired to meet before operating the OSC. If the vehicle requirements are not met whilecommanding the OSC value, an error message appears. When the error message is received,OSC is canceled.

To confirm that the scan tool sent the OSC value and the PCM has accepted the OSCsubstitution, a corresponding parameter identification (PID) for each OSC parameter must bemonitored.

One Touch Integrated Start SystemSome vehicles are equipped with one touch integrated start system. It may be necessary todisable the one touch integrated start system to carry out diagnostic procedures that requireextended cranking. Connect the scan tool, access the PCM and select the one touch integratedstart system control PID to disable the system.



Output Test Mode (OTM)

Description

WARNING: Safety must be observed when using OTM. When all outputs are on, the electric fuel pump is briefly energized. Make sure the fuel

system is intact and is not being repaired at this time. When low speed or high speed fan control(s) are turned on, make sure the fan blades

are clear of any obstruction. Failure to follow these instructions may result in personal injury.The OTM aids in diagnosing output actuators associated with the powertrain control module(PCM). This mode allows the technician to energize and de-energize most of the system outputactuators on command. When entering OTM, the outputs can be turned off and on withoutactivating the fan control. The low and high speed fan controls may be turned on separatelywithout energizing the other outputs. This function is supported by each vehicle strategy and maynot be available on all scan tools.

As a safety precaution, OTM defaults to the off state after 10 minutes, and the fuel pump off stateafter approximately 7-10 seconds. OTM also turns off after the vehicle is started or after cyclingthe key off then on.



Parameter Identification (PID)

Description

The PID mode allows access to powertrain control module (PCM) information. This includesanalog and digital signal inputs and outputs along with calculated values and the system status.There are 2 types of PID lists available and both are used throughout this manual. The first is thegeneric (J1979) OBD PID list. This is a standard set of PIDs that all scan tools must be able toaccess. The second is a Ford-specific (J2190) list which can be accessed by an appropriate scantool. When accessing any of these PIDs, the values are continuously updated. The generic or FordPID list provides definitions and values in appropriate units. For more information, refer to theSociety of Automotive Engineers (SAE) document J2205.

Generic OBD PID List

An X in the Freeze Frame column denotes both a mode 1 and mode 2 PID (real time and freezeframe).

MeasurementFreeze Frame Acronym Description Units

X AAT Ambient Air Temperature DegreesX AIR Secondary Air Status On/OffX APP D Accelerator Pedal Position D %X APP E Accelerator Pedal Position E %X APP F Accelerator Pedal Position F %X CATEMP11 Catalyst Temperature Bank 1, Sensor 1 DegreesX CATEMP12 Catalyst Temperature Bank 1, Sensor 2 DegreesX CATEMP21 Catalyst Temperature Bank 2, Sensor 1 DegreesX CATEMP22 Catalyst Temperature Bank 2, Sensor 2 Degrees

CLR DST Distance since codes cleared KmCCNT Continuous DTC Counter Unitless

X ECT Engine Coolant Temperature DegreesX EGR PCT Commanded EGR %X EGR ERR EGR Error %X EVAP PCT Commanded Evaporative Purge %X EVAP VP Evaporative System Vapor Pressure PaX EQ RAT Commanded Equivalence Ratio UnitX FUEL SYS1 Fuel System Feedback Control Status-Bank 1 OL/CL/OL

DRIVEa/OLFAULT/ CL

FAULTX FUEL SYS2 Fuel System Feedback Control Status-Bank 2 OL/CL/OL

DRIVEa/OLFAULT/ CL

FAULTIAT Intake Air Temperature Degrees

X LOADb Calculated Engine Load %(Continued)




MeasurementFreeze Frame Acronym Description Units

X LOAD ABS Absolute Load Value %X LONGFT1 Current Bank 1 Fuel Trim Adjustment %

(kamref1) From Stoichiometry Which IsConsidered Long Term

X LONGFT2 Current Bank 2 Fuel Trim Adjustment %(kamref2) From Stoichiometry Which IsConsidered Long Term

X MAF Mass Air Flow Rate gm/s-lb/minMIL DIST Distance traveled with MIL on Kilometer

X O2S11 Bank 1 Upstream Oxygen Sensor (11) VoltsX O2S12 Bank 1 Downstream Oxygen Sensor (12) VoltsX O2S13 Bank 1 Downstream Oxygen Sensor (13) VoltsX O2S21 Bank 2 Upstream Oxygen Sensor (21) VoltsX O2S22 Bank 2 Downstream Oxygen Sensor (22) VoltsX O2S23 Bank 2 Downstream Oxygen Sensor (23) Volts

OBDSUP On Board Diagnostic System OBD IIOBD IOBD

Combination ofor None

X PTO Power Take-Off Status On/OffX RPM Revolutions per Minute RPMX RUNTM Run time SecondsX SHRTFT1 Current Bank Fuel Trim Adjustment (lambse1) %

From Stoichiometry Which Is Considered ShortTerm

X SHRTFT2 Current Bank 2 Fuel Trim Adjustment %(lambse1) From Stoichiometry Which IsConsidered Short Term

X SPARKADV Spark Advance Requested DegreesX SPARK ACT Spark Advance Actual DegreesX TAC PCT Commanded Throttle Actuator %X TP Throttle Position %X TP R Relative Throttle Position %

WARM UPS Number of warm ups since codes cleared UnitsX VSS Vehicle Speed Sensor km/h-mph

a OL = Open loop, have not satisfied conditions for closed loop.b Percent engine load adjusted for atmospheric pressure.

CL = Closed loop using HO2S(s) as feedback for fuel control.OL DRIVE = Open loop due to driving conditions (heavy acceleration).OL FAULT = Open loop due to fault with all upstream HO2S sensors.

CL FAULT = Closed loop fuel control, but fault with one upstream HO2S sensor on dual bank vehicles.




Ford PID List

Note: This is not a complete list of Ford PIDs available. This is a list of Ford PIDs in this manual.

Acronym Description Ford UnitsACCS Air Conditioning Cycling Switch Input On/OffACP A/C Pressure Transducer Sensor VoltsACP A/C Pressure Transducer Sensor kPa/psiACP PRESS A/C Pressure Transducer Sensor DCV/psiACP PSI A/C Pressure Transducer Sensor psiAIR Secondary AIR Pump Control On/OffAIR F Secondary AIR Fault Indicator Yes/NoAIRM Secondary AIR Pump Monitor On/OffAPP Accelerator Pedal Position %APP1 Accelerator Pedal Position 1 VoltsAPP2 Accelerator Pedal Position 2 VoltsAPP3 Accelerator Pedal Position 3 VoltsAPP MAXDIFF Maximum Difference between APP1 and APP2 DegreesAPP MODE Accelerator Pedal Position Mode Pedal positionAXLE Axle Ratio RatioB+ Battery Voltage DCVBARO Barometric Pressure Sensor FrequencyBOO Brake Pedal Position (BPP) Switch On/OffBOO1 Brake Pedal Position (BPP) Switch On/OffBOO2 Brake Pedal Switch (BPS) On/OffBPA Brake Pedal Switch (BPS) On/OffBPP/BOO Brake Pedal Position (BPP) Switch On/OffCAT EVAL Catalyst Evaluated Yes/NoCCS Coast Clutch Solenoid Control On/OffCHT Cylinder Head Temperature Input DegreesCHT Cylinder Head Temperature Input VoltsCLRDIST Distance Since DTCs Cleared MilesCLRWRMUP Number of Warm-ups Since DTCs Cleared CountCMPFM Camshaft Position Sensor Fault Mode Yes/NoCMPFM2 Camshaft Position Sensor 2 Fault Mode Yes/NoCMP F Camshaft Position Sensor Fault Mode Yes/NoCPP Clutch Pedal Position Switch Input On/OffCPP/PNP Clutch Pedal Position/Park Neutral Position Switch Input On/OffDECHOKE Crank Fueling Disabled Yes/NoDPFEGR Differential Pressure Feedback EGR Input VoltsDRIVECNT Number of Successful Key Cycles and Engine Starts CountDTCCNT Total Number of Fault Codes Count(Continued)




Acronym Description Ford UnitsECT Engine Coolant Temperature Input DegreesECT Engine Coolant Temperature Input VoltsECT ACT Engine Coolant Temperature Degrees FECT DSD Engine Coolant Temperature Desired Degrees FEGRMC1 EGR Motor Control Output Command On/OffEGRMC2 EGR Motor Control Output Command On/OffEGRMC3 EGR Motor Control Output Command On/OffEGRMC4 EGR Motor Control Output Command On/OffEGRMDSD Electric EGR Motor Commanded in Steps On/OffEGRPCT Commanded EGR %EGRVR EGR Valve Vacuum Control %EGR EVAL EGR Evaluated Yes/NoEGR STEP EGR Valve Motor Position PositionEOT Engine Oil Temperature Sensor Input DegreesEOT Engine Oil Temperature Sensor Input Volts VoltsEOT F Engine Oil Temperature Sensor Fault Fault/No FaultEPC Electronic Pressure Control kPa/PSIEPC V Electronic Pressure Control VoltsETC ACT Electronic Throttle Control Actual DegreesETC DSD Electronic Throttle Control Desired DegreesETC TRIM Electronic Throttle Control Trim DegreesEVAP020C Evaporative Emissions Monitor Yes/NoEVAP020D Evaporative Emissions Monitor Allow/ DisallowEVAP020R Evaporative Emissions Monitor Ready/ Not ReadyEVAPCPF Evaporative Emissions Canister Purge Fault Yes/NoEVAPCV Evaporative Emissions Canister Purge Vent Control %EVAPCV F Evaporative Emissions Canister Purge Vent Fault Yes/NoEVAPPDC Evaporative Emissions Canister Purge Solenoid Duty Cycle Hz/%EVAPSOAK Evaporative Emissions Monitor Soak Conditions are Met Yes/NoEVAPSTA Evaporative Emissions Monitor Completed Cycle StatusEVAP EVAL Evaporative Emissions Monitor Evaluated Yes/NoEVMV Electronic Vapor Management Valve Commanded Current Current (mA)FANDC Variable Speed Fan Duty Cycle %FANSS Fan Speed Sensor Signal RPMFANVAR Variable Speed Fan Output %FANVAR F Variable Speed Fan Output Fault Fault/No FaultFCIL Fuel Cap Indicator Light On/OffFLI Fuel Level Indicator Input %FP Fuel Pump Duty Cycle %FPM Fuel Pump Secondary Monitor %(Continued)




Acronym Description Ford UnitsFPM Fuel Pump Secondary Monitor On/OffFRP Fuel Rail Pressure Input kPa/PSIFRP Fuel Rail Pressure Input VoltsFRP DSD Fuel Rail Pressure Desired PSIFRT Fuel Rail Temperature DegreesFRT Fuel Rail Temperature Voltage VoltsFTP Fuel Tank Pressure Input kPa/in-H2OFTP Fuel Tank Pressure Input VoltsFTP H2O Fuel Tank Pressure Input in-H2OFUELPW1 Injector Pulse Width Bank 1 MillisecondsFUELPW2 Injector Pulse Width Bank 2 MillisecondsFUELSYS Fuel System Status Open/Closed LoopFUELSYS1 Fuel System Status Bank 1 Open/Closed LoopGEAR Transmission Gear Status GearGENCMD Generator Command Yes/NoGENMON Generator Field Signal Monitor %HFC High Speed Fan Control On/OffHTR11 Bank 1 Sensor 1 HO2S Heater Control On/OffHTR11F Bank 1 Sensor 1 HO2S Heater Circuit Fault Yes/NoHTR12 Bank 1 Sensor 2 HO2S Heater Control On/OffHTR12F Bank 1 Sensor 2 HO2S Heater Circuit Fault Yes/NoHTR13 Bank 1 Sensor 3 HO2S Heater Control On/OffHTR13F Bank 1 Sensor 3 HO2S Heater Circuit Fault Yes/NoHTR21 Bank 2 Sensor 1 HO2S Heater Control On/OffHTR21F Bank 2 Sensor 1 HO2S Heater Circuit Fault Yes/NoHTR22 Bank 2 Sensor 2 HO2S Heater Control On/OffHTR22F Bank 2 Sensor 2 1 HO2S Heater Circuit Fault Yes/NoHTRCM11 Bank 1 Sensor 1 O2S Heater Circuit Current AmpsHTRCM12 Bank 1 Sensor 2 O2S Heater Circuit Current AmpsHTRCM21 Bank 2 Sensor 1 O2S Heater Circuit Current AmpsHTRCM22 Bank 2 Sensor 2 O2S Heater Circuit Current AmpsHTRX1 HO2S Sensor 1 (Upstream) Heater Control On/OffHTRX2 HO2S Sensor 2 (Downstream) Heater Control On/OffHO2S11 Bank 1 Sensor 1 HO2S Input VoltsHO2S12 Bank 1 Sensor 2 HO2S Input VoltsHO2S13 Bank 1 Sensor 3 HO2S Input VoltsHO2S21 Bank 2 Sensor 1 HO2S Input VoltsHO2S22 Bank 2 Sensor 2 HO2S Input VoltsIAC Idle Air Control %IAT Intake Air Temperature Input Degrees(Continued)




Acronym Description Ford UnitsIAT Intake Air Temperature Input Volts VoltsIAT2 Intake Air Temperature Sensor 2 Input DegreesIAT2 Intake Air Temperature Sensor 2 Input VoltsIGN R/S Ignition Switch Run/Start On/OffIMRC Intake Manifold Runner Control On/OffIMRC F Intake Manifold Runner Control Fault Yes/NoIMRC1M Intake Manifold Runner Control Monitor Input Bank 1 VoltsIMRCM Intake Manifold Runner Control Monitor Input Bank 1 VoltsIMTV Intake Manifold Tuning Valve Control %INJ1F-8F Fuel Injector Primary Fault (Cylinders 1-8) Yes/NoINJ9F-10F Fuel Injector Primary Fault (Cylinders 9 and 10) Yes/NoINJPWR M Injectors Circuit Voltage Monitor DCVISS Input Shaft Speed Hz/RPMKNOCK1 Knock Sensor 1 Signal N/AKNOCK2 Knock Sensor 2 Signal N/ALFC Low Speed Fan Control On/OffLOAD Calculated Engine Load %LONGFT Long Term Fuel Trim %LONGFT1 Long Term Fuel Trim Bank 1 %LOOP CONTRL Fuel System Status Open/Closed LoopLONGFT2 Long Term Fuel Trim Bank 2 %MAF Mass Airflow Rate Input gm/sMAF Mass Airflow Rate Input VoltsMAP Intake Manifold Absolute Pressure HzMAP Intake Manifold Absolute Pressure (Analog) VoltsMFC Medium Speed Fan Control On/OffMIL Malfunction Indicator Lamp Control On/OffMIL DIS Distance Since MIL was Activated MilesMISFIRE Misfire Status Yes/NoMP LRD Learned Misfire Correction Profile Yes/NoNM Number of Misfires CountO2BANK1 Bank 1 O2S Status Rich/LeanO2BANK2 Bank 2 O2S Status Rich/LeanO2S11 Bank 1 Sensor 1 O2S Input DCVO2S12 Bank 1 Sensor 2 O2S Input DCVO2S21 Bank 2 Sensor 1 O2S Input DCVO2S22 Bank 2 Sensor 2 O2S Input DCVO2S EVAL Oxygen Sensor Circuits Evaluated Yes/NoO2SHTR EVAL Oxygen Sensor Heater Circuits Evaluated Yes/NoOD CANCL Overdrive Cancel Function On/Off(Continued)




Acronym Description Ford UnitsOSS Output Shaft Speed RPMOSS SRC Output Shaft Speed RPMOTS STAT One Touch Integrated Start System Status Enabled/DisabledPATSENABL Passive Anti-Theft System Status Enabled/DisabledPCVHC Positive Crankcase Ventilation Heater Control PercentPSP Power Steering Pressure Switch Input High/LowPSP Power Steering Pressure Input VoltsPSP V Power Steering Pressure Input VoltsPTO Power Take Off Status Input On/OffPTOLOAD Power Take Off Engage Input Yes/NoPTOIR V Power Take Off RPM Select Input VoltsPTOIL Power Take Off Indicator Lamp Output On/OffRPM Engine Speed Based Upon CKP Input RPMRPMDSD RPM Desired RPMREV Transmission Reverse Switch Input On/OffSCB Supercharger Bypass Control On/OffSHRTFT Short Term Fuel Trim %SHRTFT1 Short Term Fuel Trim Bank 1 %SHRTFT2 Short Term Fuel Trim Bank 2 %SPARKADV Spark Advance Desired DegreesSPKDUR 1-8 Spark Duration (Cylinders 1-8) MSSS1 Shift Solenoid 1 Control On/OffSS2 Shift Solenoid 2 Control On/OffSS3 Shift Solenoid 3 Control On/OffSS4 Shift Solenoid 4 Control On/OffSTRT RLY Starter Relay Enabled/Disabled.TCC Torque Converter Clutch Control %TCIL Transmission Control Indicator Lamp Clutch Control Status On/OffTCS Transmission Control Switch (TCS) On/OffTCSS Transfer Case Speed Sensor RPMTFT Transmission Fluid Temperature Input DCV/ DegreesTFTV Transmission Fluid Temperature Input VoltsTORQUE Net Torque Into Torque Converter NmTP Throttle Position Input VoltsTP MAXDIFF Maximum Angle Difference between TP1 and TP2 DegreesTP1 Throttle Position 1 Voltage VoltsTP2 Throttle Position 2 Voltage VoltsTR Transmission Selector Position Input Status PositionTR1 Transmission Range Sensor 1 Open/ClosedTR2 Transmission Range Sensor 2 Open/Closed(Continued)




Acronym Description Ford UnitsTR3 Transmission Range Sensor 3 Open/ClosedTR4 Transmission Range Sensor 4 Open/ClosedTR V Transmission Selector Position Input Status VoltsTR D Transmission Selector Position Input Status (Digital) BinaryTRIP CNT OBD II Trips Completed CountTSS Turbine Shaft Speed/Input Shaft Speed RPMTSS/ISS Turbine Shaft Speed/Input Shaft Speed RPMTSS SRC Turbine Shaft Speed/Input Shaft Speed RPMVCTADV Variable Cam Timing Advance DegreesVCTADV2 Variable Cam Timing Advance 2 DegreesVCTADVERR Variable Cam Timing Advance Error DegreesVCTADVERR2 Variable Cam Timing Advance 2 Error DegreesVCTDC Variable Cam Timing Advance Duty Cycle %VCTDC2 Variable Cam Timing Advance Duty Cycle %VCT SYS Variable Cam Timing System Status Open Loop/ Closed

LoopVOLTDSD Desired Voltage VoltsVPWR Vehicle Power Voltage VoltsVREF Vehicle Reference Voltage VoltsVSS Vehicle Speed km/h-mphWAC/ACCR A/C Clutch Command On/OffWAC F WOT A/C Primary Circuit Fault Yes/No



Freeze Frame Data

Description

Freeze frame data allows access to emission-related values from specific generic parameteridentification (PIDs). These values are stored when an emission-related diagnostic trouble code(DTC) is stored in continuous memory. This provides a snapshot of the conditions that werepresent when the DTC was stored. Once one set of freeze frame data is stored, this data remainsin memory even if another emission-related DTC is stored, with the exception of misfire or fuelsystem DTCs. Once freeze frame data for a misfire or fuel system DTC is stored, it overwrites anyprevious data, and freeze frame data is no longer overwritten. When a DTC associated with thefreeze frame data is erased or the DTCs are cleared, new freeze frame data can be stored again.In the event of multiple emission-related DTCs in memory, always note the DTC for the freezeframe data.

FREEZE FRAME DATA TABLEAcronym Description Measurement Units

AAT Ambient Air Temperature DegreesAIR Secondary Air StatusAPP D Accelerator Pedal Position D %APP E Accelerator Pedal Position E %APP F Accelerator Pedal Position F %BARO Barometric Pressure kPaCATTEMP11 Catalyst Temperature Bank 1, Sensor 1 DegreesCATTEMP21 Catalyst Temperature Bank 2, Sensor 1 DegreesCLRDIST Distance Since Codes Cleared KmECT Engine Coolant Temperature DegreesEQ RAT Commanded Equivalence Ratio UnitEQ RAT11 Lambda Value Bank 1, Sensor 1 UnitEQ RAT21 Lambda Value Bank 2, Sensor 1 UnitEVAPPCT Commanded Evaporative Purge %EVAPVP Evaporative System Vapor Pressure PaFLI Fuel Level Input %FRP Fuel Rail Pressure kPaFUELSYS1 Open/Closed Loop 1 OL/CL/OL DRIVE/OL FAULT/CL FAULTFUELSYS2 Open/Closed Loop 2 OL/CL/OL DRIVE/OL FAULT/CL FAULTIAT Intake Air Temperature DegreesLFT1 Long Term Fuel Bank 1 %LFT2 Long Term Fuel Bank 2 %LOAD Calculated Load Value %MAF Mass Air Flow Rate g/sMAP Manifold Absolute Pressure kPaO2S11 Bank 1 Upstream Oxygen Sensor (11) Volts/mAO2S12 Bank 1 Downstream Oxygen Sensor (12) VoltsO2S21 Bank 2 Upstream Oxygen Sensor (21) Volts/mA(Continued)



Freeze Frame Data

FREEZE FRAME DATA TABLEAcronym Description Measurement Units

O2S22 Bank 2 Downstream Oxygen Sensor (22) VoltsRPM Engine RPM RPMRUNTM Run Time SecondsSFT1 Short Term Fuel Bank 1 %SFT2 Short Term Fuel Bank 2 %SPARKADV Spark Advance DegreesTAC PCT Commanded Throttle Actuator %TP Absolute Throttle Position %TP REL Relative Throttle Position %VS Vehicle Speed km/h-mphWARMUPS Number of Warmups Since Code Cleared Units

Some unique PIDs are stored in the keep alive memory (KAM) of the powertrain control module(PCM) to help in diagnosing the root cause of misfires. These PIDs are collectively called misfirefreeze frame (MFF) data. These parameters are separate from the generic freeze frame data thatis stored for every MIL code. They are used for misfire diagnosis only. The MFF data could bemore useful for misfire diagnosis than the generic freeze frame data. It is captured at the time ofthe highest misfire rate, and not when the DTC is stored at the end of a 200 or 1,000 revolutionblock. (Generic freeze frame data for misfire can be stored minutes after the misfire actuallyoccurred.)Note: MFF PIDs are supported on all vehicles, but may not be available on all scan tools

because enhanced PID access may vary by scan tool manufacturer.

MISFIRE FREEZE-FRAME PIDsPID Name Description Measurement Units

MFF RPM Engine RPM at the time of misfire RPMMFF LOAD Engine load at the time of misfire %MFF VSS Vehicle speed at the time of misfire km/h-mphMFF IAT Intake air temperature at the time of misfire DegreesMFF SOAK Engine-off soak time at the time of misfire TimeMFF RNTM Engine running time at the time of misfire TimeMFF EGR EGR DPFE sensor at the time of misfire VoltsMFF TP Throttle Position at time of misfire VoltsMFF TRIP Number of driving cycles at the time of Number of Trips

misfire (at least one 1,000 rev block)MFF PNP 1= in DRIVE during the time of misfire ModeMP LRN 1= Misfire wheel profile learned in KAM Yes/No



Flash Electrically Erasable Programmable Read OnlyMemory (EEPROM)

Description

The EEPROM is contained in an integrated circuit internal to the powertrain control module (PCM).The EEPROM contains the vehicle strategy including calibration information specific to the vehicle,and is capable of being programmed or flashed repeatedly.

As part of the calibration there is an area referred to as the vehicle identification (VID) block. TheVID block is programmed when installing a new PCM as described under Programming the VIDBlock for a Replacement PCM. Failure to carry out this procedure may generate DTCs P1635 orP1639. The VID block in an existing PCM can also be tailored to accommodate various hardwareor parameter changes made to the vehicle since production. Failure to carry out this procedureproperly may generate DTC P1635, Tire/Axle Ratio out of Acceptable Range. An incorrect tire/axleratio is one of the main causes for DTC P1639. This is described under Making Changes to theVID Block and also under Making Changes to the PCM Calibration. The VID block contains manyitems used by the strategy for a variety of functions. Some of these items include the vehicleidentification number (VIN), octane adjust, fuel octane, fuel type, vehicle speed limit, tire size, axleratio, the presence of speed control, and 4-wheel drive electronic shift-on-the-fly (ESOF) versusmanual shift-on-the-fly (MSOF). Only items applicable to the vehicle hardware and supported bythe VID block is displayed on the scan tool.

When changing items in the VID block, the strategy places range limits on certain items such astire and axle ratio. The number of times the VID block may be reconfigured is limited. When thislimit is reached, the scan tool displays a message indicating the need to flash the PCM again toreset the VID block.

Programming can be carried out by a local Ford dealer or any non-Ford facility. Refer to the scantool manufacturers instruction manual for details.

Programming the VID Block for a Replacement PCM

A new PCM contains the latest strategy and calibration level for a particular vehicle. However, theVID block is blank and needs programming. There are 2 procedures available. The first is anautomatic data transfer from the old PCM to the new PCM, and the second is manual data entryinto the new PCM.

Automatic data transfer is carried out if the old PCM is capable of communicating. This is done byusing a scan tool to retrieve data from the old PCM before removing it from the vehicle. Thestored data can then be downloaded to the new PCM after it has been installed.



Flash Electrically Erasable Programmable Read OnlyMemory (EEPROM)

Carry out manual data entry if the old module is damaged or incapable of communicating. Removeand install a new PCM. Using a compatible scan tool, select and carry out the module/parameterprogramming, referring to the scan tool manufacturers instruction manual. Make certain that allparameters are included. Failure to properly program tire size in revolutions per mile, (rev/mileequals 63,360 divided by the tire circumference in inches), axle ratio, 4x4/4x2, and/or MSOF/ESOFmay result in DTCs P1635 and P1639. You may be instructed to contact the As-Built Data Centerfor the information needed to manually update the VID block with the scan tool. Contact the centeronly if the old PCM cannot be used or the data is corrupt. For Ford and Lincoln Mercurytechnicians, contact your National Hotline or the Professional Technician Society (PTS) website forAs-Built data listed under the Service Publications Index. Non-Ford technicians use theMotorcraft website at www.motorcraft.com. From the Motorcraft homepage, use the searchfunction to find the Module Programming or As-Built Data.

For Ford and Lincoln Mercury technicians, check the Programmable Module Installation link on thePTS website for quick Programmable Module data information by vehicle.

Making Changes to the VID Block

A PCM which is programmed may require changes to be made to certain VID information toaccommodate the vehicle hardware. Refer to Module Reprogramming on the scan tool.

Making Changes to the PCM Calibration

At certain times, the entire EEPROM needs to be completely reprogrammed. This is due tochanges made to the strategy or calibration after production, or the need to reset the VID blockbecause it has reached its limit. Refer to Module Reprogramming on the scan tool.



Diagnostic Monitoring Test Results Mode 6

Mode 6 allows access to the results of on board diagnostic (OBD) monitor diagnostic test results.The test values are stored at the time of the particular monitor completion. Refer to mode 6 on thescan tool for test information.



On Board Diagnostic (OBD) Drive Cycle

Description of On Board Diagnostic (OBD) Drive CycleThe following procedure is designed to execute and complete the OBD monitors and to clear theFord P1000, I/M readiness code. To complete a specific monitor for repair verification, follow steps1 through 4, then continue with the step described by the appropriate monitor found under theOBD Monitor Exercised column. For the EVAP/secondary AIR monitor to run, the ambient airtemperature must be between 4.4 to 37.8C (40 to 100F), and the altitude below 2,438 meters(8,000 feet). If the P1000 code must be cleared in these conditions, the powertrain control module(PCM) must detect them once (twice on some applications) before the EVAP monitor can bebypassed and diagnostic trouble code (DTC) P1000 is cleared. The EVAP bypassing procedure isdescribed in the following drive cycle.

The OBD drive cycle is carried out using a scan tool. Refer to the manufacturers instructionmanual for each described function.

A detailed description for clearing the DTCs is found in this section. Refer to Clear The ContinuousDiagnostic Trouble Codes (DTCs) And Reset The Emission Monitors Information in The PowertrainControl Module (PCM).

Drive Cycle Recommendations

WARNING: Strict observance of posted speed limits and attention to drivingconditions are mandatory when proceeding through the following drive cycles. Failure tofollow these instructions may result in personal injury.1. Most OBD monitors complete more readily using a steady foot driving style during cruise or

acceleration modes. Operating the throttle in a smooth fashion minimizes the time required formonitor completion.

2. The fuel tank level should be between 1/2 and 3/4 full with 3/4 full being the most desirable.

3. The evaporative monitor can operate only during the first 30 minutes of engine operation.When executing the procedure for this monitor, stay in part throttle mode and drive in a smoothfashion to minimize fuel slosh.

4. When bypassing the EVAP engine soak times, the PCM must remain powered (key ON) afterclearing the continuous DTCs and relearning emission diagnostic information.

For best results, follow each of the following steps as accurately as possible:




OBD MonitorExercised Drive Cycle Procedure Purpose of Drive Cycle ProcedureDrive Cycle Bypasses the engine soak timer. Resets theNote:Preparation OBD monitor status.To bypass the EVAP soak

timer (normally 6 hours), thePCM must remain poweredafter clearing the continuousDTCs and resetting theemission monitors informationin the PCM.

1. Install the scan tool. Turn the key on with theengine off. Cycle the key off, then on. Ifneeded, select the appropriate vehicle andengine qualifier. Clear the continuous DTCs andreset the emission monitors information in thePCM.2. Begin to monitor the following PIDs (ifavailable): ECT, EVAPDC, FLI and TP MODE.Start the vehicle without returning the key to theOFF position.3. Idle the vehicle for 15 seconds. Drive at 64 Executes SEC AIR flow check monitor (ifkm/h (40 mph) until the engine coolant applicable).temperature (ECT) is at least 76.7C (170F).

Prep for 4. Is the intake air temperature (IAT) between Engine warm-up and provides IAT input to theMonitor Entry 4.4 to 37.8C (40 to 100F)? If not, complete PCM.

the following steps, but note that step 14 isrequired to bypass the EVAP/secondary AIRmonitor and clear DTC P1000.

HEGO 5. Cruise at 64 km/h (40 mph) for at least 5 Executes the HO2S monitor.minutes.

EVAP 6. Cruise at 64 to 89 km/h (40 to 55 mph) for Executes the EVAP monitor if the IAT is10 minutes (avoid sharp turns and hills). NOTE: between 4.4 to 37.8C (40 to 100F).To initiate the monitor, the throttle should be atpart throttle, EVAPDC must be greater than75%, and FLI must be between 15 and 85%,and for fuel tanks over 25 gallons FLI must bebetween 30 and 85%.

Catalyst 7. Drive in stop and go traffic conditions. Executes the catalyst monitor.Include 5 different constant cruise speeds,ranging from 32 to 89 km/h (20 to 55 mph) overa 10 minute period.

EGR 8. From a stop, accelerate to 72 km/h (45 mph) Executes the EGR monitor.at 1/2 to 3/4 throttle. Repeat 3 times.

SEC AIR/CCM 9. Bring the vehicle to a stop. Idle with the Executes the idle air control (IAC) portion of the(Engine) transmission in drive (neutral for M/T) for 2 comprehensive component monitor (CCM) and

minutes. the SEC AIR functional check (if applicable).(Continued)




OBD MonitorExercised Drive Cycle Procedure Purpose of Drive Cycle Procedure

CCM 10. For M/T, accelerate from 0 to 81 km/h (0 to Executes the transmission portion of the CCM.(Transmission) 50 mph), and continue to step 12. For A/T, from

a stop and in overdrive, moderately accelerateto 81 km/h (50 mph) and cruise for at least 15seconds. Stop the vehicle and repeat withoutoverdrive to 64 km/h (40 mph) cruising for atleast 30 seconds. While at 64 km/h (40 mph),activate the overdrive, accelerate to 81 km/h(50 mph) and cruise for at least 15 seconds.Stop for at least 20 seconds and repeat step 10five times.

Misfire and Fuel 11. From a stop, accelerate to 97 km/h (60 Allows learning for the misfire monitor.Monitors mph). Decelerate at closed throttle to 64 km/h

(40 mph) (no brakes). Repeat this 3 times.Readiness 12. Access the On-Board System Readiness Determines if any monitor has not completed.

Check (OBD monitor status) function on the scan tool.Determine whether all non-continuous monitorshave completed. If not, go to step 13.

Pending Code 13. With the scan tool, check for pending Determines if a pending code is preventing theCheck and codes. Conduct the normal repair procedures clearing of DTC P1000.

EVAP Monitor for any pending code concern. Otherwise,Bypass Check repeat any incomplete monitor. If the EVAP

monitor or SEC AIR monitor is not completeand the IAT was out of the 4.4 to 37.8C (40 to100F) temperature range in step 4, or thealtitude is over 2438 m (8000 ft.), the EVAPbypass procedure must be followed. Go to Step14.

EVAP Monitor 14. Park the vehicle for a minimum of 8 hours. Allows the bypass counter to increment to 2.Bypass Repeat steps 2 through 11. Do not repeat step

1.



Intermittent Diagnostic Techniques

Intermittent diagnostic techniques help find and isolate the root cause of intermittent concernsassociated with the electronic engine control (EEC) system. The information is organized to helpfind the concern and carry out the repair. The process of finding and isolating an intermittentconcern starts with recreating a fault symptom, accumulating powertrain control module (PCM)data, and comparing that data to typical values, then analyzing the results. Refer to the scan toolmanufacturers instruction manual for the functions described below.

Before proceeding, be sure that: Customary mechanical system tests and inspections do not reveal a concern. NOTE: Mechanical

component conditions can make a PCM system react abnormally. Technical Service Bulletins (TSBs) and On-line Automotive Service Information System (OASIS)

messages, if available, are reviewed. Quick Test and associated diagnostic subroutines have been completed without finding a

concern, and the symptom is still present.

Recreating the Fault

Recreating the concern is the first step in isolating the cause of the intermittent symptom. Athorough investigation should start with the customer information worksheet located in the back ofthis manual. If freeze frame data is available, it may help in recreating the conditions at the time ofa malfunction indicator lamp diagnostic trouble code (MIL DTC). Listed below are some of theconditions for recreating the concern:

CONDITIONS TO RECREATE FAULTNon-Engine Type Condi-

Engine Type Conditions tionsEngine Temperature Ambient TemperatureEngine RPM Moisture ConditionsEngine Load Road Conditions

(smooth-bumpy)Engineidle/accel/deceleration

Accumulating PCM Data

PCM data can be accumulated in a number of ways. This includes circuit measurements with adigital multimeter (DMM) or scan tool parameter identification (PID) data. Acquisition of PCM PIDdata using a scan tool is one of the easiest ways to gather information. Gather as much data aspossible when the concern is occurring to prevent improper diagnosis. Data should beaccumulated during different operating conditions and based on the customer description of theintermittent concern. Compare this data with the known good data values located in Section 6Typical Diagnostic Reference Values. This requires recording data in 4 conditions for comparison:1) KOEO, 2) Hot Idle, 3) 48 km/h (30 mph), and 4) 89 km/h (55 mph).



Intermittent Diagnostic Techniques

Comparing PCM Data

After the PCM values are acquired, it is necessary to determine the concern area. This typicallyrequires the comparison of the actual values from the vehicle to the typical values from the Section6 Typical Diagnostic Reference Values. The charts apply to different vehicle applications (engine,model, transmission).

Analyzing PCM Data

Look for abnormal events or values that are clearly incorrect. Inspect the signals for abrupt orunexpected changes. For example, during a steady cruise most of the sensor values should berelatively stable. Sensors such as throttle position (TP), mass air flow (MAF), and RPM thatchange abruptly when the vehicle is traveling at a constant speed are clues to a possible concernarea.

Look for an agreement in related signals. For example, if the APP1, APP2, or APP3, is changedduring acceleration, a corresponding change should occur in idle air control (IAC), RPM, andSPARK ADV PID.

Make sure the signals act in proper sequence. An increase in RPM after the TP1 and TP2 isincreased is expected. However, if the RPM increases without a TP1 and TP2 change, a concernmay exist.

Scroll through the PID data while analyzing the information. Look for sudden drops or spikes in thevalues.



Adaptive Fuel Diagnostic Trouble Code (DTC) DiagnosticTechniques

The Adaptive Fuel DTC Diagnostic Techniques help isolate the root cause of the adaptive fuelconcern. Before proceeding, attempt to verify if any driveability concerns are present. Thesediagnostic aids are meant as a supplement to the pinpoint test steps in Section 5. For adescription of fuel trim, refer to Section 1, Powertrain Control Software, Fuel Trim.

Obtain Freeze Frame Data

Freeze frame data is helpful in duplicating and diagnosing adaptive fuel concerns. The data (asnapshot of certain parameter identification (PID) values recorded at the time the DTC is stored inContinuous Memory) is helpful to determine how the vehicle was being driven when the concernoccurred, and is especially useful on intermittent concerns. Freeze frame data, in many cases,helps to isolate possible areas of concern as well as rule out others. Refer to Freeze Frame Datain this section for a more detailed description of this data.

Using the LONGFT1 and LONGFT2 (Dual Bank Engines) PIDsThe LONGFT1/2 PIDs are useful for diagnosing fuel trim concerns. A negative PID value indicatesthat fuel is being reduced to compensate for a rich condition. A positive PID value indicates thatfuel is being increased to compensate for a lean condition. It is important to know that there is aseparate LONGFT value that is used for each RPM/load point of engine operation. When viewingthe LONGFT1/2 PIDs, the values may change a great deal as the engine is operating at differentRPM and load points. This is because the fuel system may have learned corrections for fueldelivery concerns that can change as a function of engine RPM and load. The LONGFT1/2 PIDsdisplay the fuel trim currently being used at that RPM and load point. Observing the changes inLONGFT1/2 can help when diagnosing fuel system concerns. For example: A contaminated mass air flow (MAF) sensor results in matching LONGFT1/2 correction values

that are negative at idle (reducing fuel), but positive (adding fuel) at higher RPM and loads. LONGFT1 values that differ greatly from LONGFT2 values rule out concerns that are common

for both banks (for example, fuel pressure concerns, MAF sensor, etc. can be ruled out). Vacuum leaks result in large rich corrections (positive LONGFT1/2 value) at idle, but little or no

correction at higher RPM and loads. A plugged fuel filter results in no correction at idle, but large rich corrections (positive

LONGFT1/2 value) at high RPM and load.Resetting Long Term Fuel Trims

Long term fuel trim corrections are reset by resetting the keep alive memory (KAM). Refer toResetting The Keep Alive Memory (KAM) in this section. After making a fuel system repair, theKAM must be reset. For example, if dirty/plugged injectors cause the engine to run lean andgenerate rich long term corrections, installing new injectors and not resetting the KAM causes theengine to run very rich. The rich correction eventually leans out during closed loop operation, butthe vehicle may have poor driveability and high CO emissions while it is learning.




DTCs P0171/P0174 System Too Lean Diagnostic Aids

Note: If the system is lean at certain conditions, then the LONGFT PID would be a positive valueat those conditions, indicating that increased fuel is needed.

The ability to identify the type of lean condition causing the concern is crucial to a correctdiagnosis.

Air Measurement System

With this condition, the engine runs rich or lean of stoichiometry (14.7:1 air/fuel ratio) if thepowertrain control module (PCM) is not able to compensate enough to correct for the condition.One possibility is that the mass of air entering the engine is actually greater than what the MAFsensor is indicating to the PCM. For example, with a contaminated MAF sensor, the engine runslean at higher RPM because the PCM delivers fuel for less air than is actually entering the engine.Examples: The MAF sensor measurement is inaccurate due to a corroded connector, contaminated or dirty

connector. A contaminated MAF sensor typically results in a rich system at low airflows (PCMreduces fuel) and a lean system at high airflows (PCM increases fuel).

Vacuum Leaks/Unmetered Air

With this condition, the engine runs lean of stoichiometry (14.7:1 air/fuel ratio) if the PCM is notable to compensate enough to correct for the condition. This condition is caused by unmetered airentering the engine, or due to a MAF concern. In this situation, the volume of air entering theengine is actually greater than what the MAF sensor is indicating to the PCM. Vacuum leaks arenormally most apparent when high manifold vacuum is present (for example, during idle or lightthrottle). If freeze frame data indicates that the concern occurred at idle, a check for vacuumleaks/unmetered air is the best starting point. Examples: loose, leaking, or disconnected vacuum lines intake manifold gaskets, or O-rings throttle body gaskets brake booster air inlet tube stuck/frozen/aftermarket positive crankcase valve (PCV) unseated engine oil dipstick.

Insufficient Fueling




With this condition, the engine runs lean of stoichiometry (14.7:1 air/fuel ratio) if the PCM is notable to compensate enough to correct for the condition. This condition is caused by a fuel deliverysystem concern that restricts or limits the amount of fuel being delivered to the engine. Thiscondition is normally apparent as the engine is under a heavy load and at high RPM, when ahigher volume of fuel is required. If the freeze frame data indicates that the concern occurs undera heavy load and at higher RPM, a check of the fuel delivery system (checking fuel pressure withengine under a load) is the best starting point. Examples: low fuel pressure (fuel pump, fuel filter, fuel leaks, restricted fuel supply lines) fuel injector concernsExhaust System Leaks

In this type of condition, the engine runs rich of stoichiometry (14.7:1 air/fuel ratio) because thefuel control system is adding fuel to compensate for a perceived (not actual) lean condition. Thiscondition is caused by oxygen (air) entering the exhaust system from an external source. TheHO2S reacts to this exhaust leak by increasing fuel delivery. This condition causes the exhaustgas mixture from the cylinder to be rich. Examples: exhaust system leaks upstream or near the HO2S cracked/leaking HO2S boss inoperative secondary air injection systemDTCs P0172/P0175 System Too Rich Diagnostic Aids

Note: If the system is rich at certain conditions, then the LONGFT PID would be a negative valueat that airflow, indicating that decreased fuel is needed.

System rich concerns are caused by fuel system concerns, although the MAF sensor and baseengine (for example, engine oil contaminated with fuel) should also be checked.Air Measurement System

With this condition, the engine runs rich or lean of stoichiometry (14.7:1 air/fuel ratio) if the PCM isnot able to compensate enough to correct for the condition. One possibility is that the mass of airentering the engine is actually less than what the MAF sensor is indicating to the PCM. Forexample, with a contaminated MAF sensor, the engine runs rich at idle because the PCM deliversfuel for more air than is actually entering the engine. Examples: MAF sensor measurement inaccurate due to a corroded connector, contamination/dirt. A

contaminated MAF sensor typically results in a rich system at low airflows (PCM reduces fuel)and a lean system at high airflows (PCM increases fuel).

Fuel System

With this condition, the engine runs rich of stoichiometry (14.7:1 air/fuel ratio), if the PCM is notable to compensate enough to correct for the condition. This situation causes a fuel deliverysystem that is delivering excessive fuel to the engine.




Examples: fuel pressure regulator causes excessive fuel pressure (system rich at all airflows), fuel pressure

is intermittent, going to pump deadhead pressure, then returning to normal after the engine isturned off and restarted.

fuel pulse dampener diaphragm ruptured (fuel leaking into the intake manifold, system rich atlower airflows).

fuel injector leaks (injector delivers extra fuel). EVAP canister purge valve leak (if the canister is full of vapors, introduces extra fuel). fuel rail pressure (FRP) sensor (electronic returnless fuel systems) concern causes the sensor to

indicate a lower pressure than actual. The PCM commands a higher duty cycle to the fuel pumpdriver module (FPDM), causing high fuel pressure (system rich at all airflows).

Air Inlet System

A restriction within any of the following components may be significant enough to affect the abilityof the PCM adaptive fuel control. air inlet tube air cleaner element

air cleaner assembly resonators

clean air tube

Base Engine

Engine oil contaminated with fuel can contribute to a rich-running engine.


diagnostic methods

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