natef task area a-5 brake systems

2013 NATEF Task Area A-5

Brake Systems7-2013

• A. General Brake System Diagnosis

• B. Hydraulic System Diagnosis & Repair

• C. Drum Brake Diagnosis & Repair

• D. Disc Brake Diagnosis & Repair

• E. Power Assist Diagnosis & Repair

• F. Wheel Bearing, Parking Brake, Electrical D & R

• G. Anti-lock Brake & Traction Control Systems

NATEF Task Area A-5 Brake Systems

A. General Brake System Diagnosis

Identify and interpret brake system concerns; determine necessary action. A5.A.1

P-1



Research applicable vehicle and service information, such as brake system

operation, vehicle service history, service precautions, and technical service

bulletins.

A5.A.2

P-1



Describe procedure for performing a road test to check brake system operation;

including an anti-lock brake system (ABS). Consider doing it in a parking lot!

A5.A.3

P-1

A brake inspection should consist of:

1. A road test to check brake operation

2. A wheels-off inspection to measure brake rotor

thickness. Every brake rotor has a spec for thickness to

ensure safe operation. When they are outside this

measurement, they cannot be used.

3. Measuring the thickness of the brake material to

determine if it is above a minimum thickness. The brake

pads not only provide the necessary friction, but also help

dissipate heat. If pads are too thin, they cannot perform

these two important functions.

4. Inspecting the brake calipers for damage such as torn

dust boots, sticking pistons, etc. If the brake calipers are

not performing as designed, they will not allow enough

force to be applied to the brake pads to stop the vehicle.

The feel and sound of ABS.

When ABS is activated, you may experience a slight vibration or a rapid pulsation of the brake pedal almost as if

the brakes are pushing back at you. At times, you will feel the pedal suddenly drop. The valves in the ABS unit

may make a grinding, scraping or buzzing noise. This means your ABS is working. Continue to apply firm

pressure and steer. Do not take your foot off the brake pedal.



Install wheel and torque lug nuts. A5.A.4

P-1



Complete work order to include customer information, vehicle identifying

information, verify customer concern, related service history, cause, correction.

Have the Customer Sign & Date the R.O.

“Oldie”



Locate and interpret vehicle and major component identification numbers (VIN,

vehicle certification labels, calibration decals).

“Oldie”


B. Hydraulic System Diagnosis & Repair

Diagnose pressure concerns in the brake system using hydraulic principles

(Pascal’s Law).

A5.B.1

P-1



Measure brake pedal height, travel, and free play (as applicable); determine

necessary action.

A5.B.2

P-1



Check master cylinder for internal/external leaks and proper operation; determine

necessary action.

A5.B.3

P-1



Remove, bench bleed, and reinstall master cylinder. A5.B.4

P-1



Diagnose poor stopping, pulling or dragging concerns caused by malfunctions in

the hydraulic system; determine necessary action.

A5.B.5

P-3



Inspect brake lines, flexible hoses, and fittings for leaks, dents, kinks, rust, cracks,

bulging, and wear; check for loose fittings & supports; determine necessary action.

A5.B.6

P-1



Replace brake lines, hoses, fittings, and supports. A5.B.7

P-2



Fabricate brake lines using proper material and flaring procedures (double flare

and ISO types).

A5.B.8

P-2



Select, handle, store, and fill brake fluids to proper level. A5.B.9

P-1

http://www.meder.com/fileadmin/meder/pdf/en/Technical_Documents/Technical_Write-Ups/Brake_Fluid_Level_Sensor_Application.pdf



Inspect, test, and/or replace components of brake warning light system. A5.B.10

P-3



Identify components of brake warning light system. A5.B.11

P-3



Inspect, test, replace metering (hold-off), proportioning (balance), pressure

differential, & combination valves.

“Oldie”



Inspect, test, replace, and adjust height (load) sensing proportioning valve. “Oldie”



Bleed and/or flush brake system. A5.B.12

P-1


1. B. Hydraulic System Diagnosis & Repair

Flush hydraulic system. “Oldie”



Test brake fluid for contamination. A5.B.13

Green: Battery OK, i.e.: No water contained in the

brake fluid.

Yellow: Less than 1% of water content in brake

fluid.

Yellow/ Yellow: Approx. 2% of water content in

brake fluid.

Yellow/ Yellow/ Red: Approx. 3% water content in

brake fluid. The brake fluid should be changed.

Yellow/ Yellow/ Red/ Red: At least 4% of water

content in brake fluid. The brake fluid must be

changed urgently.

P-1


C. Drum Brake Diagnosis & Repair

Diagnose poor stopping, noise, vibration, pulling, grabbing, dragging or pedal

pulsation concerns; determine necessary action.

A5.C.1

P-1



Remove, clean, inspect, and measure brake drum diameter; determine necessary

action.

A5.C.2

P-1



Refinish brake drum & measure final drum diameter; compare with specifications. A5.C.3

P-1



Remove, clean, and inspect brake shoes, springs, pins, clips, levers, adjusters/self-

adjusters, other related brake hardware, and backing support plates; lubricate and

reassemble.

A5.C.4

P-1



Inspect wheel cylinders for leaks & proper operation; remove & replace as needed. A5.C.5

P-2



Pre-adjust brake shoes and parking brake; install brake drums or drum/hub

assemblies and wheel bearings; perform final checks and adjustments.

A5.C.6

P-2


D. Disc Brake Diagnosis & Repair

Diagnose poor stopping, noise, vibration, pulling, grabbing, dragging, or pulsation

concerns; determine necessary action.

A5.D.1

P-1



Remove and clean caliper assembly; inspect for leaks and damage/wear to caliper

housing; determine necessary action.

A5.D.2

P-1



Clean and inspect caliper mounting and slides/pins for proper operation, wear, and

damage; determine necessary action.

A5.D.3

P-1



Remove, inspect, and replace pads and retaining hardware; determine necessary

action.

A5.D.4

P-1



Disassemble and clean caliper assembly; inspect parts for wear, rust, scoring, and

damage; replace seal, boot, and damaged or worn parts.

“Oldie”



Lubricate and reinstall caliper, pads, and related hardware; seat pads and inspect

for leaks.

A5.D.5

P-1



Clean and inspect rotor; measure rotor thickness, thickness variation, and lateral

runout; determine necessary action.

A5.D.6

P-1



Remove and reinstall rotor. A5.D.7

P-1



Refinish rotor on vehicle; measure final rotor thickness and compare with

specifications.

A5.D.8

P-1



Refinish rotor off vehicle; measure final rotor thickness and compare with

specifications.

A5.D.9

P-1



Retract and re-adjust caliper piston on an integrated parking brake system. A5.D.10

P-3



Check brake pad wear indicator; determine necessary action. A5.D.11

P-2



Describe importance of operating vehicle to burnish/break-in replacement brake

pads according to manufacturer’s recommendations.

A5.D.12

30/30/30 Burnish Procedure

• Perform 30 stops from 30 miles per hour with a

30-second cooling interval between stops. These

stops will be performed at a decelerating rate of 12

feet per second or less. This means that it should be

a gentle easy stop.

• The 30/30/30 Burnish Procedure beds the pads and

shoes into the rotor and drums. It also deposits the

necessary friction transfer to the rotors and drums

for optimum brake performance.

• Following this procedure also assures that your

customer will have excellent brake performance

from the first time he or she drives the car after

brake service has been performed. You should not

depend on your customer to break in the brake job.

The only way to assure that it is done correctly is to

incorporate it into your brake job test drive.

P-1


E. Power Assist Units Diagnosis & Repair

Check brake pedal travel with, and without, engine running to verify proper power

booster operation.

A5.E.1

P-2



Check vacuum supply (manifold or auxiliary pump) to vacuum-type power

booster.

A5.E.2

P-1



Inspect vacuum-type power booster unit for leaks; inspect the check-valve for

proper operation; determine necessary action.

A5.E.3

P-1

http://image.superchevy.com/f/13001390/sucp_0901_03_z+power_brake_boosters+dual_diaphragm.jpg



Inspect and test hydraulically-assisted power brake system for leaks and proper

operation; determine necessary action.

A5.E.4

P-3



Measure and adjust master cylinder pushrod length. A5.E.5

P-3


F. Wheel Bearing, Parking Brake, Electrical Diagnosis & Repair

Diagnose wheel bearing noises, wheel shimmy, and vibration concerns; determine

necessary action.

A5.F.1

P-3



Remove, clean, inspect, repack, and install wheel bearings; replace seals; install

hub and adjust bearings.

A5.F.2

P-1



Check parking brake cables and components for wear, binding, and corrosion;

clean, lubricate, adjust or replace as needed.

A5.F.3

P-2



Check parking brake operation and parking brake indicator light system

operation; determine necessary action.

A5.F.4

P-1



Check operation of brake stop light system. A5.F.5

P-1



Replace wheel bearing and race. A5.F.6

P-2



Remove and reinstall sealed wheel bearing assembly. A5.F.7

P-2



Inspect and replace wheel studs A5.F.8

P-2


G. Anti-lock Brake & Traction Control Systems

Identify and inspect electronic brake control system components; determine

necessary action.

A5.G.1

P-1



Identify traction control/vehicle stability control system components. A5.G.2

P-3



Describe the operation of a regenerative braking system. A5.G.3

P-3



Diagnose poor stopping, wheel lock-up, abnormal pedal feel, unwanted application,

and noise concerns associated with the electronic brake control system ; determine

necessary action.

A5.G.4

P-2



Diagnose electronic brake control system electronic control(s) and components by

retrieving diagnostic trouble codes, and/or using recommended test equipment;

determine necessary action.

A5.G.5

P-2



Depressurize high-pressure components of an electronic brake control system. A5.G.6

P-3



Bleed the electronic brake control system hydraulic circuits. A5.G.7

P-1



Remove and install anti-lock brake system (ABS) electrical/electronic and

hydraulic components.

“Oldie”



Test, diagnose, and service electronic brake control system speed sensors (digital

and analog), toothed ring (tone wheel), and circuits using a graphing multi-meter

(GMM)/digital storage oscilloscope (DSO) (includes output signal, resistance,

shorts to voltage/ground, and frequency data).

A5.G.8

P-3



Diagnose electronic brake control system braking concerns caused by vehicle

modifications (tire size, curb height, final drive ratio, etc.).

A5.G.9

P-3

Interaction Between the ABS System & a Compact Spare

Because ABS brakes monitor wheel rpm, any

difference in wheel rpm “confuses” the ABS

system, causing it to activate even on dry roads.

Because a compact (“donut”) spare rotates faster

than a normal tire, this difference “kicks-in” the

ABS system when you don’t expect it. Some car

models disable the ABS by a connector attached to

the spare. Be sure to reconnect this when

replacing your spare.

Note that if you change tire size (such as smaller

front tires), you may affect your car’s computers,

such as ABS, fuel, traction control, etc. Check

with your tire dealer to learn how tire size

differences may impact your car.

ABS Light + Check Tire Pressure Light Problems