chapter 20 bennet

7/26/2019 Chapter 20 Bennet

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Chapter 20

Electronically

Automated StandardTransmissions


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Objectives (1 of 2)

Explain how a standard mechanical transmission isadapted for automated shifting in three-pedal andtwo-pedal systems.

Identify three different OEM automatedtransmissions and interpret the serial number codesof each.

Describe the hardware changes that differentiate astandard Roadranger twin-countershaft

transmission from its electronically automatedversion.

Outline the electronic circuit components that areused to manage AutoShift transmissions.


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Objectives (2 of 2)

Outline the main box and auxiliary section actuator

components required for AutoShift electronically

automated, standard transmissions.

Describe how the electronic circuit componentswork together to perform the system functions.

Perform some basic diagnostic troubleshooting on

automated transmission electronics.

Describe the ZF Meritor SureShift and FreedomLinetransmissions and the Mercedes Benz AGS

transmissions.


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Transmission Identification

The best way of identifying transmission

specifications on a vehicle is by accessing

the chassis data bus, specifically the 130

MID for generic ESTs.


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AutoShift (1 of 2)

Serial Number: RTAO14710 B AS

R Roadranger

T Twin countershaft

A Automated

O Overdrive (X)100 + 50 = nominal torque capacity

7 Design level (5 = spur gear, 6 = multimesh gearing,7 = multimesh front, helical auxiliary gearing)

10 Number of forward speeds

B Ratio set designation (C) AS AutoShift


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AutoShift (2 of 2)


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UltraShift

Serial number: RTO - 14 9 10 B - DM 2

R Roadranger

T Twin countershaft

O Overdrive 14 Torque capacity

9 Design level

10 Forward speeds

B Ratio category DM UltraShift with DM clutch

2 Automation level/Gen II electronics


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Freedomline

Serial Number: M O16 Z 10 C - A 18

M ZF Meritor

O Overdrive (no letter = direct drive)

16 Input torque rating: 1,600 lb./ft. Z Design platform: Z = FreedomLine F = 9 speed

G = 10 speed

10 Number of forward gears

C Ratio A Automated (S = shift by wire, M = manual)

18 Highest torque in top 2 gears = 1800 lb./ft.


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Mercedes Benz AGS

Serial Number: MBT560 S - 6 O

MBT Mercedes-Benz Transmission

560 Input torque rating 560 lb./ft.

6 Number of forward ratios

O Overdrive (D 5 direct drive)


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UltraShift Two-pedal

Automated Transmission


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Mercedes-Benz AGS

Two-pedal Automated Transmission


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AutoShift Components

The Eaton Fuller Roadranger AutoShift automatedtransmission is a two-module system.

The System Manager (ECU) does the thinking.

A second module, the transmission controller (ECU),

converts that thinking into action by performing theswitching functions of the transmission.

AutoShift transmission components can be groupedas follows:

Base standard gearbox Transmission automation components

Vehicle automation components


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Base Transmission

The AutoShift transmission is based on a Roadranger twin-countershaft platform.

A Fuller 10-speed transmission has a 5-speed main or frontcase, with a 2-speed auxiliary section.

Although the base transmission has a similar appearance tonon-automated versions, the following changes are required:

Main box. Two screw bosses have been added to the case sothe transmission controller can be mounted to the side.

Range cylinder cover. The range cylinder cover is altered tohouse the range shift control mechanism.

Shift bar housing. The shift bar housing has been machined toaccept the speed sensors.

Shift yokes. The shift yokes have been hardened at the forkpads to improve durability during shifts.


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Automation Components

The transmission automation components

include:

XY shifter

Speed sensors

Power module

Transmission harness

Range valve Reverse switch

Transmission controller


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Electric Shifter Assemblies

The shift shaft is a squaresection shaft.

The shift finger rides on theshift shaft.

This permits the shift finger tobe moved along the rail.

The shift shaft has a machinedarea on the end to enable it torotate the position sensor.

The gear select yoke alsorides on the shift shaft. Theyoke is driven by the gearselect ball screw, whichrotates the shift shaft for gearselection.

The gear select sensorprovides position data to thetransmission controller.


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Ball Screw Assemblies (1 of 2)

The shift finger position is located by a pair of

ball screws.

One ball screw is used for the lateral (left to

right) movement that is required to select thecorrect rail.

The other ball screw is used for the forward

or backward positioning required to select agear.


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Ball Screw Assemblies (2 of 2)

The ball screw assembly ismade up of a worm gear,ball screw nut, and ballbearings.

When the worm gear

rotates, the ball bearingsride in the grooves of theworm threads.

When a ball reaches theend of a ball screw block, it

is forced into a tube to bereturned to the beginning ofthe worm threads in the ballscrew block.


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Rail Select Ball Screw

The gear select ball screw nut has a pair of

tabs, one on either side.

These tabs drive the gear select yoke, which

is located on the shift shaft with the shiftfinger.

When gear selection is commanded, the ball

screw block moves the gear select yoke,which in turn moves the shift shaft.


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Electric Motors

The motors use apermanent magnetoperating principle and arecapable of forward orreverse rotation.

The rail select motor ispinned directly to the railselect ball screw and thegear select motor is pinneddirectly to the gear select

ball screw. The electric motors used in

each ball screw assemblyare not interchangeable.


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Position Sensors (1 of 2)

Position sensors convert amechanical position to asignaled voltage value that isthen returned to the ECU.

AutoShift position sensors arethree-wire voltage dividers.

They are supplied a referencevoltage of 5V, modulated bythe ECU.

There is a resistor betweenthe 5V input terminal and theground connection.

A wiper contacts the resistorand, depending on itsmechanical location,determines the signal voltagevalue returned to the ECU.


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Position Sensors (2 of 2)

The rail select sensor is connected to the rail select

ball screw. The position sensor yoke arm fits over a

pin on the side of the rail select screw block. Its

signal allows the transmission controller to

determine whether the shift finger is located over

the correct rail before effecting a shift.

The gear select sensor monitors shift finger position

during gear selection. The signal returned to thetransmission controller confirms whether a shift has

been successfully effected.


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Shop Talk

Current versions of AutoShift are designed to

break driveline torque when a predetermined

driveline (road) speed is sensed.

This prevents driveline component stalldamage to the engine.


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Range Valve Operation (1 of 2)


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Range Valve Operation (2 of 2)


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Speed Sensors (1 of 4)

Three speed sensors are usedin the transmission. Theymeasure and report: Input shaft speed

Mainshaft speed

Output shaft speed

When the teeth of the pulsewheel cut through themagnetic field in the sensor,an AC voltage is induced inpulses.

The AC voltage value and

frequency produced will rise inproportion to the increase inrotational speed.

These sensors can be testedby measuring voltage output.


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The input shaft speed sensoris located at the right frontcorner of the shift rail housing.

The speed sensor magnet andcoil produce pulses from the

upper countershaft PTO gear. The AC voltage and frequency

rise proportionally with shaftspeed.

The ECU measures thefrequency of the pulses, notthe actual voltage generated.

Input shaft speed is calculatedby multiplying countershaftspeed by the head set ratio.


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The mainshaft speed sensor is located at theleft rear corner of the shift rail housing at theauxiliary countershaft drive gear.

A pulse generator principle is used; the ACvoltage and frequency produced and sent tothe ECU increase proportionally with shaftrotational speed.

The auxiliary countershaft drive gear ismeshed to the mainshaft through theauxiliary drive gear and is driven at the samespeed.


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The output shaft speed sensor picks up pulses

produced by a tone ring located on the output shaft.

This tailshaft-located sensor inputs road speed data

to the AutoShift transmission controller and to other

chassis electronic systems.

Road speed is determined by factoring the output

shaft speed with the drive axle carrier ratio and the

rolling radius dimension of the tires. A standard 16-tooth pulse wheel is used.


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Function of the Speed Sensors

Shift synchronization Input shaft speed and mainshaft speed data is used by

the transmission controller for synchronizing shifts inthe transmission main box.

Verifies range engagement The data generated by the mainshaft and output shaft

speed sensors is used by the transmission controller toverify range engagement.

Reports road speed data The output or tailshaft speed sensor data may also beshared with other chassis electronic systems as vehicleroad speed data.


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Power Module (1 of 2)

The power module is locatedon the transmission controllernext to the electric shifter unit.It incorporates the followingcomponents: Cycling circuit breakers

Reverse voltage diode Reverse voltage Zener diode

The power module connectsthe vehicle electrical systemwith the transmission electricaland electronic systems and

protects the transmissionelectrical system from currentoverloads with cycling-typecircuit breakers.


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Power Module (2 of 2)

The AutoShift power modulecontains two SAE #1 cyclingcircuit breakers:

One rated at 25 amps. The25-amp breaker protects

the circuit supplying theelectric shifter motors andthe logic battery powerfrom current overloads.

The other at 10 amps. The10-amp breaker is locatedin series in the circuitsupplying logic batterypower following the 25-amp breaker.


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Reverse Voltage Diode

The reverse voltage diode is located just past the

25-amp circuit breaker. The diode permits current

flow in one direction only. In the event of a reversepolarity condition, the reverse voltage diode blocks

current flow into the transmission electrical circuit.


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Reverse Voltage Zener Diode

The reverse voltage zener diode is located between the negativeterminal on the reverse voltage diode and battery ground.

The zener diode functions as a normal diode but acts to regulate

voltage should it exceed a specified level. The reverse voltage zener diode used in the AutoShift power

module will permit current flow, although it will not permit thevoltage value to exceed 32V.


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Power Module Functions

Motor Power. Connected to the vehicle cranking motor, the circuit passes throughthe 25-amp circuit breaker and the reverse voltage diode and connects to themotor terminals.

Motor ground. The motor is direct grounded through the power module by means

of a wire to the cranking motor ground terminal. Logic power. Logic power refers to the electric feed required to power up the

system ECUs. It is routed from the vehicle cranking motor battery terminal throughboth the 25-amp and 10-amp circuit breakers.

Logic ground. The logic ground is routed direct from the cranking motor groundterminal through the power module and out to the logic power connector.

T i i C ll


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Transmission Controller

It has some limited processingcapability but is mainlyresponsible for managing theswitching requirements of thesystem.

The transmission controller

ECU is multiplexed. It is connected to the system

electrical/electronic circuit bymeans of a dedicated harnessknown as the transmissionharness.

All of the input and outputcircuits are connected to thetransmission controller bymeans of this harness,including the data link to thesystem manager.

I ti B k


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Inertia Brake

The inertia brake system onan AutoShift transmissionhelps stop the countershaftson initial engagements whenthe clutch is either out ofadjustment or defective.

The inertia brake is mountedat the 6- or 8-bolt PTO.

The inertia brake consists of asolenoid and brake.

The solenoid controls theinertia brake by switching

regulated air pressure to theinertia brake piston to applythe friction and reaction discs,which brakes the countershaft.

C ti


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Caution

When removing the inertia brake solenoid,ensure that system air pressure is completely

relieved and the air/filter regulator is

removed.

Vehicle Automation


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Vehicle Automation

Components

The vehicle automation components connect thetransmission electrical and electronic circuits with

those of the vehicle. This group of components

includes:

System manager

Gear display

Shift lever

Power connect relay

Start enable relay

Vehicle harnesses

S t M


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System Manager

The system manager ECU is a secondmicroprocessor module with the dual functions of

interfacing with the rest of the vehicle and overall

management of the transmission systems.

Controlling logic power

Managing shifting

Processing fault conditions

Processing shift lever commands

Controlling Service and Wait lights

Providing information to lever digital display

C ti


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Caution

The shifter module must be calibrated beforea vehicle is placed in operation.

Data Retention


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Data Retention

The system manager stores fault code datain its nonvolatile RAM before turning off the

power connect relay during each shutdown.


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Service light

The service light displays

fault information to thedriver or technician.

A flashing or continuous

illumination of the service

light indicates that a fault

code has been logged. Logged fault codes can

then be pulse displayed

by flashing numeric codes

on the service light.

Wait light

The wait light was only

used on the earliest

versions of

AutoSelect/AutoShift.

On those transmissions

using a wait light, it is

illuminated on power-upwhen the system manager

and transmission controller

perform a self-check

sequence.

If the transmission checksokay, the wait light turns off.

S k Detents


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Speaker

The speaker tone is

used to alert the driverto break torque on the

driveline so that a shift

can be effected.

The tone signal is

output by the system

manager.

Detents

The detent mechanism

locates the

transmission shift lever

in the correct location

in each range select

position.

It provides an elementof gearshift feel to the

driver when shifting

from one gear to

another.

Gear Display


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Gear Display

When a shift is initiated, thetarget gear is displayedcontinuously.

When the transmission shiftsto neutral, the target gearbegins to flash.

When the shift sequence iscompleted, the display ceasesto flash and the range status isdisplayed.

Up arrows indicate the inputshaft speed must be increased

until it matches main shaftspeed.

Down arrows indicate theinput shaft speed must bedecreased to match the mainshaft speed.

Vehicle Harnesses (1 f 2)


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Vehicle Harnesses (1 of 2)



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Tower Harness Service Port


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Tower Harness Service Port

The service port is located inthe tower harness. It is used toaccess circuits for voltagechecks. The circuits can bechecked without separatingharness connectors.

Pin A: ignition power

Pin B: dummy

Pin C: measures voltage atthe power connect relay

Pin D: ground

Pin E: start enable relay coil Pin F: dummy

Pin G: power connect relaycoil; output from the systemmanager

Fallback Modes


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Fallback Modes

When a fault code is logged, the transmissionelectronics are designed to assess all

remaining functionality and then default to a

limited operational mode. Five-speed fallback

One-speed fallback

In-place fallback

Downshift fallback

Fault Code Status


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Fault Code Status

An active code indicates a problem active at thetime of reading the system.

An inactive code (historic code) indicates theoccurrence of a fault that has either occurred in thepast or is not detected at the moment of reading the

system. The presence of an inactive code may indicate that

the vehicle has not been driven in the propermanner.

AutoShift system troubleshooting should beperformed using the AutoShift service literature thatcontains step-by-step troubleshooting guides.

Pretests


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Pretests

Transmission pretests should be performedbefore progressing to specific fault codeisolation.

Pre-checks require that electrical inputs andpneumatic supply to the transmission befunctioning properly.

The pretests eliminate obvious high-level

problems immediately before progressing toa detailed, sequentially stepped diagnosticprocedure.

Symptom-driven Diagnostics


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Symptom driven Diagnostics

No fault codeA transmission is, above all, a mechanical

device, and problems will occur in which

active or inactive electronic codes are notlogged.

Mechanical faults

Never assume that every fault must be

electronically monitored.

CEEMAT


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CEEMAT

This was an early, not too successful effortby Eaton at an automated transmission

system.

The acronym stands for converter enhanced,electronically managed, automated

transmission.

You do see a few CEEMAT automated

transmissions around, but more likely in a

college or teaching environment rather than

on the highway.

Engine SynchroShift (ESS)


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Engine SynchroShift (ESS)

Rockwell Meritor introduced Engine SynchroShift (ESS) in 1997just before their merger with the German company ZF.

ESS is a three-pedal system designed to synchronize enginerpm automatically to road speed during any shift sequence.

The ESS transmission had no independent processing capabilityand relied upon multiplexing to the engine electronics to operate.

The end result was to make the shifting of a non-synchronizedmanual transmission as easy as shifting a fully synchronizedtransmission. As a three-pedal system, the main function of the clutch was to

break driveline torque at stall; that is, for starting and stoppingthe vehicle.

Auxiliary range shifts were automatic, reducing driver effort andsynchronizer damage.

ESS featured a break torque switch that enabled the driver topower upshift and downshift.

SureShift


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SureShift

SureShift is a ZF Meritor three-pedal automatedtransmission that uses joystick initiated shifts.

The clutch pedal is used only to break driveline

torque at stall (starting and stopping).

SureShift is currently available in 9- and 10-speed

transmissions.

The electronics are J1939 networked to the chassis

data bus. The system is essentially a later versionof the ESS system.

FreedomLine


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FreedomLine

The ZF Meritor FreedomLine transmission was thefirst two-pedal system automated transmissionavailable for trucks.

The driver can select either automatic or manual

modes of operation, but he has no direct controlover clutching.

A self-adjusting system-actuated clutch is built intothe FreedomLine automated transmission.

It is available in 12- and 16-speed versions. FreedomLine transmissions are networked into the

chassis data bus via a J1939 data link.

Mercedes-Benz AGS


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The automated transmission is an adaptation of the Mercedes-Benz six-speed, medium-duty, mechanical transmission that hasbeen around for a number of years.

It is packaged into an aluminum housing and uses a two-pedalsystem with a manual option mode.

When operated in manual mode, the management electronicsprevent the driver from making a shift that could result indriveline damage.

It is networked to the J1939 data bus so that shift algorithms arebased in what is happening elsewhere in the engine anddrivetrain.

Troubleshooting is accomplished using Freightliner ServiceProsoftware.

UltraShift


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The UltraShift automated transmission wasintroduced by Eaton Fuller Roadranger in 2003 asa two-pedal system. The initial release was a 10-speed unit with an inertia brake.

UltraShift uses a modular automation design that is

said to simplify service repair work. The clutch usedis a 15.5 inch, two-plate, ceramic button type withcoaxial springs.

In common with all current automatedtransmissions, the driver can option manual shifting.

The Eaton Gen II software is programmed withalgorithms that prevent the driver from making ashift that could result in driveline damage.

Urge to Move


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g

The latest innovation from Eaton Fuller is the addition of a fullyautomated wet clutch to their six-speed AutoShift transmissionused in medium-duty applications.

This converts their automated transmission into a two-pedalsystem that handles similarly to an equivalent Allison automatictransmission.

To make the wet clutch perform much like an automatic with atorque converter, Eatons wet clutch uses a creep feature knownas Urge-to-Move.

Urge-to-Move loads a continuous 45 pounds-feet of torque to thetransmission through the wet-clutch pack so that the driversenses engagement at any time the shift lever is in the driveposition.

This system requires a cooler for the transmission fluid.

Summary (1 of 6)


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y ( )

Automated standard transmissions use electroniccontrols to adapt a standard mechanicaltransmission for either semi-automated or fullyautomated shifting. This technology allows thedriver to keep both hands on the steering wheelduring shifting and significantly reduces driverfatigue.

Automated transmissions can be divided into three-pedal systems that use a clutch pedal and two-

pedal systems that eliminate the clutch pedal. Allautomated transmissions use a clutch, but theclutch is controlled by the system electronic controlunit (ECU).

Summary (2 of 6)


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y

The Eaton Fuller AutoShift transmission is based ona standard Roadranger twin countershaftmechanical transmission platform. AutoShiftelectronics use two ECUs to perform logicprocessing and output switching operations

required by the system. The AutoShift system manager ECU performs most

of the processing. It manages transmission functions and information,

interfaces with the chassis data bus, controls shifting

through its handshake connection with the transmissioncontroller, acts on driver command signals, performsdiagnostic self-checks, and logs fault codes.

Summary (3 of 6)


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The AutoShift transmission controller managesshifting based on command signals received fromthe system manager, monitors the input circuitcomponents physically located within thetransmission, exchanges speed and gear ratiostatus data with the system manager, and providesthe system manager with diagnostic information.

The AutoShift system manager ECU is located inthe shift tower assembly.

The transmission controller ECU is located on theleft side of the transmission.

Summary (4 of 6)


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Shifts are effected by an electric shifter assembly that replacesthe gear shift lever in a standard Roadranger transmission. Apair of reversing electric motors actuated by the transmissioncontroller precisely locates a shift finger in the shift blockrecesses in the shift rails.

The rail select motor is used to move the shift finger transversely(side to side) with the objective of locating it precisely in the shiftrecess of one of the three shift rails.

The gear select motor moves forward and backward. After theshift finger has been positioned over the correct shift rail, thegear select motor is energized to move the rail into gear.

Summary (5 of 6)


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The means used by automated transmissions toselect gears is identical to that in a standardtransmission: shift finger movement first selects oneof the three shift rails, then slides that rail fore or aft.

AutoShift transmissions perform self-diagnostic

tests and log fault codes when performanceparameters of any electronically monitoredcomponent or system are out of specification.Faults are broadcast over the chassis data bus.

Fault codes can be displayed by the AutoShiftdiagnostic (service) lights, or by either using ahandheld diagnostic EST or a PC with theappropriate software.

Summary (6 of 6)


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The electronics are SAE J1939 compatible,which permits multiplexing with other chassis

electronics systems.

Most of the automated transmissions thatcompete with the AutoShift system are

similar in terms of their principles of

operation.

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