38S08T0 advanced brake systems diagnosis and service 2005

Prereq - 1 LESSON ONE-MODULE 1: ADVANCED BRAKE SYSTEM THEORY AND OPERATION INTRODUCTION TO ABS AND TRACTION CONTROL SYSTEMS .... Course Objective Given the information presented in the F

Diagnosis and

Service

Student Guide

Appropriate service methods and proper repair procedures are essential for the safe, reliable operation of all motor vehicles,

as well as the personal safety of the individual doing the work This manual provides general directions for accomplishing service and repair work with tested, effective techniques Following them will help assure reliability.

There are numerous variations in procedures, techniques, tools and parts for servicing vehicles, as well as in the skill of the individual doing the work This manual cannot possibly anticipate all such variations and provide advice or cautions as to each Accordingly, anyone who departs from instructions provided in this manual must first establish that he compromises neither his personal safety nor the vehicle integrity by his choice of methods, tools or parts.

As you read through the procedures, you will come across NOTES, CAUTIONS, and WARNINGS Each one is there for a specific purpose NOTES give you added information that will help you to complete a particular procedure CAUTIONS are given to prevent you from making an error that could damage the vehicle WARNINGS remind you to be especially careful

in those areas where carelessness can cause personal injury The following list contains some general WARNINGS that you should follow when you work on a vehicle.

• Always wear safety glasses for eye protection.

• Use safety stands whenever a procedure requires you to

be under the vehicle.

• Be sure that the ignition switch is always in the OFF

position, unless otherwise required by the procedure.

• Set the parking brake when working on the vehicle If you

have an automatic transmission, set it in PARK unless

instructed otherwise for a specific service operation If

you have a manual transmission it should be in

RE-VERSE (engine OFF) or NEUTRAL (engine ON) unless

instructed otherwise for a specific service operation.

• Operate the engine only in a well-ventilated area to avoid

the danger of carbon monoxide.

• Keep yourself and your clothing away from moving parts

when the engine is running, especially the fan and belts.

• To prevent serious burns, avoid contact with hot metal parts such as the radiator, exhaust manifold, tail pipe, catalytic converter and muffler.

• Do not smoke while working on the vehicle.

• To avoid injury, always remove rings, watches, loose hanging jewelry, and loose clothing before beginning to work on a vehicle Tie long hair securely behind your head.

• Keep hands and other objects clear of the radiator fan blades Electric cooling fans can start to operate at any time by an increase in underhood temperatures, even though the ignition is in the OFF position Therefore, care should be taken to ensure that the electric cooling fan is completely disconnected when working under the hood.

The recommendations and suggestions contained in this manual are made to assist the dealer in improving his dealership parts and/or service department operations These recommendations and suggestions do not supersede or override the provisions of the Warranty and Policy Manual, and in any cases where there may be a conflict, the provisions of the Warranty and Policy Manual shall govern.

The descriptions, testing procedures, and specifications in this handbook were in effect at the time the handbook was approved for printing Ford Motor Company reserves the right to discontinue models at any time, or change specifications, design, or testing procedures without notice and without incurring obligation Any reference to brand names in this manual

is intended merely as an example of the types of tools, lubricants, materials, etc recommended for use Equivalents, if available, may be used The right is reserved to make changes at any time without notice.

WARNING: Many brake linings contain asbestos fibers When working on brake components, avoid breathing the dust Breathing

the asbestos dust can cause asbestosis and cancer.

Breathing asbestos dust is harmful to your health.

Dust and dirt present on car wheel brake and clutch assemblies may contain asbestos fibers that are hazardous to your health when made airborne by cleaning with compressed air or by dry brushing.

Wheel brake assemblies and clutch facings should be cleaned using a vacuum cleaner recommended for use with asbestos fibers.

5. Provide me with a clear and thorough explanation of the service performed.

after my service visit to ensure that I'm completly satisfied.

bring to your attention.

serviced at your dealership.

a genuine concern for my service needs.

and professional manner.

Expectation 3

“Fix It Right The First Time, On Time.”

Both service advisors and technicians are important players when it comes to Expectation

It is our goal to help the technician acquire all of the skills and knowledge necessary to “Fix

It Right The First Time, On Time.” We refer to this as “competency.”

Technician’s Role

Acquire the skills and knowledge for competency in your specialty via:

The Benefits

The successful implementation of expectations means:

CUSTOMER EXPECTATIONS

Customer Expectations: Service

INTRODUCTION AND PREREQUISITE REVIEW

FORD BRAKES SERVICE TECHNICIAN SPECIALITY TRAINING (STST) CURRICULUM Intro - 2 Curriculum Goals Intro - 2 Advanced Brake System Diagnosis and Service Instructor-Led Course Description Intro - 2 Course Objective Intro - 2 Lesson Objectives Intro - 2 Audience Intro - 2 Course Prerequisites Intro - 2 Evaluation Intro - 3 Student Guide Intro - 3 Course Agenda Intro - 3 Service Standards Intro - 4 PREREQUISITE REVIEW Prereq - 1

LESSON ONE-MODULE 1: ADVANCED BRAKE SYSTEM THEORY AND OPERATION

INTRODUCTION TO ABS AND TRACTION CONTROL SYSTEMS 2

OVERVIEW OF ABS OPERATION 3

ABS Operation-Normal Braking 4

ABS Operation - Brake Pressure Hold 5

ABS Operation - Brake Pressure Decrease 6

ABS Operation - Pump/Motor Running 7

Traction Control Operation 8

Advance Trac/ Electronic Stability assist System 10

LESSON ONE WORKSTATIONS 13

WORKSTATION 1 14

WORKSTATION 2 15

WORKSTATION 3 16

WORKSTATION 4 18

LESSON ONE-MODULE 2: ADVANCED BRAKE SYSTEM COMPONENTS Anti-lock Brake System (ABS) Components and Operation 22

ABS/Traction Control/Advance Trac Inputs and Outputs Chart 23

ANTI-LOCK BRAKE SYSTEM (ABS) CONTROL MODULE 24

HYDRAULIC CONTROL UNIT (HCU) 27

ABS INPUT DEVICES 29

Powertrain Control Module (PCM) 29

Wheel Speed Sensors and Wheel Speed Sensor Indicators 31

Passive Anti-Lock Brake Sensors 31

Yaw Rate Sensor (Advance Trac System Only) 44

Lateral Accelerometer (Advance Trac System Only) 45

Roll Stability Control (RSC) 46

Steering Wheel Rotation Sensor (Advance Trac System Only) 47

Active Brake Booster 48

ABS OUTPUT DEVICES 51

Inlet/Isolation Solenoid 52

Outlet/Dump Solenoid 53

Traction Control (TC) Inlet/Isolation Solenoid 54

Pump/Motor Assembly 55

ABS Power Relay 56

ABS Warning Light 57

LESSON TWO DEMONSTRATION 3 - ADVANCE TRAC CALIBRATION PROCEDURES 59

LESSON TWO WORKSTATIONS 63

WORKSTATION 1A 64

WORKSTATION 2A 65

WORKSTATION 3A 66

WORKSTATION 4A 68

ADVANCED BRAKE SYSTEM DIAGNOSIS AND SERVICE ANTI-LOCK BRAKE SYSTEM (ABS) DIAGNOSIS AND SERVICE 72

Common Customer Concerns 73

Diagnostic Trouble Code (DTC) Diagnosis 73

Hydraulic Components 74

Inlet/Isolation Valve 74

Outlet/Dump Valve 74

Unwarranted ABS Operation (ABS Misfire, ABS Too Sensitive, ABS Fires On Normal Stop) 75

ABS Concerns 75

Base Brake/Vehicle Concerns 75

Diagnosing Unwarranted ABS Operation 75

Wheel Lock Up 76

ABS Concerns 76

Base Brake/Vehicle Concerns 76

Wheels Lockup Diagnosis 76

Hard or Soft Brake Pedal 77

ABS Concerns 77

Base Brake/Vehicle Concerns 77

Hard or Soft Brake Pedal Diagnosis 77

Vehicle Pulls 78

ABS Concerns 78

Base Brake/Vehicle Concerns 78

Vehicle Pulls Diagnosis 78

ABS ELECTRONICS DIAGNOSIS 79

ABS Warning Indicator Always On With System Pass (No Codes or a Pass Code) 79

ABS-Warning-Indicator-Always-On-With-System-Pass Diagnosis 79

No Communication With ABS Electronic Control Module 79

No-Communication-With-ABS-Electronic-Control-Module Diagnosis 79

ADVANCE TRAC DIAGNOSIS AND SERVICE PROCEDURES 80

ABS BLEEDING PROCEDURES 84

WORKSTATION 2B 87

WORKSTATION 3B 88

WORKSTATION 4B 91

DEMONSTRATION 4 - ABS BLEEDING 93

LESSON THREE WORKSTATIONS 97

WORKSTATION 1 98

WORKSTATION 2 99

WORKSTATION 3 100

WORKSTATION 4 102

GLOSSARY

TOOL LIST

ROTUNDA ORDER FORM

INTRODUCTION

Curriculum Goals

The goals of this curriculum are to provide:

Right The First Time On Time” repairs

Advanced Brake System Diagnosis and Service Instructor-Led Course Description

This is the second instructor-led course in the Brakes Curriculum It is a three-day course facilitated

by an instructor This course is designed to provide hands-on opportunities for technicians to learn and improve their skills using tools and equipment; and to apply knowledge learned in previous curriculum courses.

Course Objective

Given the information presented in the Ford Advanced Brake System Diagnosis and Service

Course, the necessary service information and tools, technicians will be able to perform accurate, timely, cost-effective diagnosis and repair of ABS, Traction Control, and Advance Trac braking and stability assist systems on Ford Motor Company vehicles.

Lesson Objectives

Each lesson of this course starts with a list of objectives for the participants The lesson objectives are designed to support the course objective.

Audience

This course is designed for any Ford and Lincoln and Mercury service technicians who are enrolled

in the Ford Brakes Service Technician Speciality Training (STST) Curriculum Additionally, this course

is also designed for training service technicians of Ford Designated Fleets.

Vehicle Brake Systems Web Based Training - Course Code 38S01W0

Brake Service Procedures Web Based Training - Course Code 38S02W0

Brake System Diagnosis and Repair Instructor-Led Training - Course Code 38S07T0

ABS Theory and Operation Web Based Training - Course Code 38S03W0

ABS Diagnosis Web Based Training - Course Code 38S04W0

The Ford Brakes Service Technician Speciality Training (STST) Curriculum consists of seven courses related to brake system diagnosis and service Each course in the curriculum is a “building block” for the next course in the curriculum.

This curriculum is designed for technicians who want to learn the methods and techniques to

properly diagnose and service brake systems and components.

FORD BRAKES SERVICE TECHNICIAN SPECIALITY TRAINING (STST) CURRICULUM

Courses of The Ford Brakes Service Technician Speciality Training (STST) Curriculum

Each technician attending this course will be required to pass a combination hands-on/written evaluation This will be administered on the afternoon of the third day The hands-on evaluation is a pass/fail type.

In order to pass the course, you must demonstrate acceptable skills at the evaluated hands-on

exercises AND you must answer at least 80% of the written post test questions correctly.

Student Guide

The Student Guide contains the worksheets used at the workstations for each of the three days You must complete each worksheet.

IMPORTANT: Actively participate in exercise reviews This is your opportunity to ask questions

and clear up any areas that you may not fully understand.

Course Agenda

Lesson One: Morning - Prerequisite Review, Module 1 Advanced Brake System Theory and Operation, 4 workstations.

Afternoon - Module 2 Advanced Brake System Components, Demonstration 1, Demonstration 2.

Lesson Two: Morning - Review Lesson One, Demonstration 3, 4 workstations.

Afternoon - Lesson Two Advanced Brake System Diagnosis and Service, 4 workstations.

Lesson Three: Review Lesson Two, Demonstration 4, 4 workstations.

Afternoon - Post Test.

SERVICE STANDARDS

Mission Statement

All dealership personnel will treat every customer as a potential lifetime purchaser, communicating

a professional image that embraces honesty and concern for customer wants and needs.

Dealer-to-Customer Service Standards

cus-tomer.

Standard 4

Vehicles Serviced Right on the First Visit:

The technician is the most important player when it comes to Standard 4.

“Fix it Right the First Time, on Time”

The technician’s role is to acquire the skills and knowledge for competency in your specialty via:

INTRODUCTION

REVIEW

Directions: Select the best answer for the questions listed on the following pages.

1 Which of the following components controls the operation of the anti-lock brake system?

A ABS Control Module

B Hydraulic Control Unit (HCU)

C Brake Pressure Control Valve

D Anti-Lock Main Power Relay

2 If the ABS module detects possible wheel lockup, it sends electrical signals to the:

A Powertrain Control Module (PCM)

B Hydraulic Control Unit (HCU)

C Master cylinder

D Wheel speed sensor

3 Active wheel speed sensors are two-wire sensors, but they can NOT be tested using:

A Ohmmeter

B NGS

C WDS

D All of the above

4 What is the purpose of the traction control system?

A Help enhance stability during maneuvers

B Control a vehicles wheel spin during acceleration

C Help prevent wheel lock-up during braking

D All of the above

5 A typical ABS system operates in what mode(s):

A Brakes not applied

B Normal braking

C Anti-lock Mode

D All of the above

6 What function does the Advance Trac system perform?

A Controls wheel spin during hard acceleration

B Automatically switches from 2-wheel to 4-wheel drive

C Prevents wheel lock up during hard braking

D Helps the driver maintain vehicle stability and steerability

7 Which system uses an active brake booster?

A Advance Trac system

B Traction Control system

C ABS system

D None of the above

8 The anti-lock brake warning indicator is a/an _ warning lamp located in the instrument cluster

A is ok, but there is a problem with the base brakes

B has not completed the self-check

C has completed the self-check

D requires service

10 When diagnosing an ABS concern, the first step that should always be performed is to:

A perform a visual inspection

B verify the concern

C retrieve ABS DTCs

D refer to the symptom chart in the workshop manual

PREREQUISITE REVIEW

11 The Active Brake Booster is activated during which of the following conditions?

A Severe stability control events

B Anytime the Advance Trac system is activated

C During ABS events

D All of the above

12 On diagnostic scan tools the Advance Trac system is referred to as:

A Traction Control

B ABS System

C Stability Assist

D Interactive Vehicle Dynamics (IVD)

13 Where is the steering wheel rotation sensor located?

A On the steering knuckle

B On the steering column

C On the steering shaft

D In the steering Wheel

14 What methods may be used to maintain traction on traction control equipped vehicles other than application

of the brakes?

A Throttle control

B Adjustment of spark timing

C Fuel injector control

D All of the above

A Pump and Motor assembly

B Inlet/Isolation Valve

C Outlet/Dump Valve

D All of the above

16 How does the anti-lock braking system help prevent lock-up?

A By modulating the hydraulic pressure sent to the front and rear brakes

B With special brake pads that supply greater friction

C By sending electronic signals to the wheel calipers

D By equalizing hydraulic pressure during braking

17 Which of the following statements apply if there is a fault in the ABS system?

A The base brake system will not work

B The base brake system will continue to operate

C The traction control system will continue to operate

D The Advance Trac system will continue to operate

18 Technician A says that ABS diagnosis procedures are found in the workshop manual Technician B says thatthe ABS PIDs can be viewed using the WDS Who is right?

A Technician A

B Technician B

C Both Technician A and B

D Neither Technician A or B

19 Which of the following is a common cause for intermittent ABS concerns?

A Poor electrical contact at wiring connectors

B Poor electrical grounds

C Loose sensors

D All of the above

A monitoring the active brake booster for faults.

B traction control inlet/isolation valve control.

C pump and motor control.

D monitoring the base brake mechanical system for faults.

C Pump and Motor Assembly

D All of the above

22 Following the SSCC diagnostic process, what should be done after determining the faulty system?

A Find the faulty component

B Verify the concern

C Determine the cause of the concern

D Test-drive the vehicle

23 If the Advance Trac Off light is illuminated it may indicate all of the following EXCEPT:

A That there is a fault in the Traction Control system

B That there is a fault in the Advance Trac system

C That there is a fault in the ABS system

D That the driver has disabled the Advance Trac system

24 Which is the best method to determine if the pump and motor functions properly?

A Using jumper wires to send power to the pump and motor

B Checking for DTCS

C During the road test performing several ABS stops and listening for activation

D Using the active command function of a scan tool

A PC/ED

B Workshop Manuals

C Wiring Diagrams (EVTM)

D Owners Guide

Upon completion of this lesson the student will be able to:

– Identify the characteristics of Anti-lock Brake, Traction Control, and Advance Trac systems

– Describe the operation of Anti-lock Brake, Traction Control, and Advance Trac systems

– Locate the components of Anti-lock Brake, Traction Control, and Advance Trac systems

ADVANCED BRAKE SYSTEM THEORY

AND OPERATION

MODULE 1

LESSON ONE-MODULE 1 ADV BRAKE SYSTEM THEORY & OPERATION

INTRODUCTION TO ABS, TRACTION CONTROL, AND STABILITY ASSIST SYSTEMS

As you have learned while taking the web-based training in this curriculum, the purpose of Anti-lock BrakeSystems (ABS) is to provide the driver with the best possible vehicle control when braking

Many ABS systems include a Traction Control function that helps maintain vehicle traction during accelerationand driving

Additionally, the new Advance Trac system that is being introduced on many vehicles helps to maintainvehicle stability while driving and maneuvering

This lesson will describe the theory and operation of these systems in order to help you perform diagnosis andservice

OVERVIEW OF ABS OPERATION

The purpose of the Anti-Lock Brake Systems (ABS) is to prevent lock up of the front and rear wheels during anemergency stop This is achieved by modulating the hydraulic pressure sent to the front and rear brakes

ABS helps the driver to maintain steering control and bring the vehicle to a stop in the shortest possibledistance under most conditions

The pedal effort and pedal feel during normal braking conditions is similar to a conventional power brakesystem

During anti-lock braking, the driver will feel a pulsation in the brake pedal and hear a clicking sound caused

by the actuation of the solenoids and valves in the Hydraulic Control Unit (HCU)

The operation of modern anti-lock brake systems is controlled by the ABS control module, which is often referred

to as the Electronic Control Unit (ECU) When the ignition key is in the RUN position, the ABS control module isactivated The control module then uses wheel speed sensors to monitor wheel rotational speed

When the driver depresses the brakes, the Brake On/Off (BOO) switch closes, informing the ABS control module

to be prepared to activate anti-lock operation if necessary

If the ABS control module senses impending wheel lockup, it closes the inlet valve, preventing further lic pressure from reaching the wheel cylinders or calipers

hydrau-
The ABS control module checks wheel speed again If potential wheel lock up is still possible, it rapidlypulses the outlet/dump valve, located in the Hydraulic Control Unit (HCU), allowing brake fluid to flow fromthe wheel cylinders or calipers to the accumulator, releasing hydraulic pressure This reduces the brakingaction to the affected wheel(s)

The ABS control module then pulses the inlet/isolation and outlet/dump solenoid valves in a manner that willkeep the wheels rotating while still maintaining high levels of deceleration

During an anti-lock stop, pressure in the hydraulic system is maintained by the pump and motor assembly

When an anti-lock event occurs, the ABS control module energizes a relay that activates the pump motor Thepump pushes any hydraulic fluid that enters the accumulator back into the hydraulic system

Once the operator releases the brake pedal, the inlet/isolation valve de-energizes and any fluid in the lator is pumped back into the master cylinder Normal brake operation resumes

accumu-
The function of the accumulator is to temporarily store fluid purged from the caliper during an ABS event

Driving Conditions

The amount of brake pedal force required to engage the ABS function will vary with road conditions

Brake lockup is more likely to occur on a wet, snow covered, or icy road, or as a result of a sudden reaction bythe driver due to an unexpected obstacle During these situations the wheels may lockup

If the wheels lockup the vehicle may start to skid, resulting in complete loss of driver control To prevent this

LESSON ONE-MODULE 1 ADV BRAKE SYSTEM THEORY & OPERATION

HCU

During normal braking, when the brakes are applied:

Fluid is forced from the master cylinder to the normally open isolation/inlet solenoid valves of the HCU

The brake fluid travels through the HCU uninterrupted to the braking units like in a normal brake system

ABS Operation-Normal Braking

1

2

3

4 5 6

Pump and Motor

Accumulator

Outlet/Dump Valve (Closed)

Brake Caliper Inlet/Isolation Valve (Open) BOO Switch

ABS Operation During Normal Braking

1

2

3 4

6

5

If the driver gets into a situation where the brakes are applied hard enough to cause a wheel lock up:

The ABS control module will send signals to the HCU

The HCU uses these signals to prevent wheel lock up from occurring

ABS Operation - Brake Pressure Hold

1

2

3 4

Pump and Motor

Accumulator

Outlet/Dump Valve (Closed)

Brake Caliper Inlet/Isolation Valve (Closed) BOO Switch

ABS Operation During Brake Pressure Hold

LESSON ONE-MODULE 1 ADV BRAKE SYSTEM THEORY & OPERATION

HCU

The ABS control module then looks at the wheel speed signal again:

If the affected wheel is still decelerating too quickly, the control module sends a signal to the HCU that

opens the dump/outlet valve for that circuit

This dumps pressure from the brake to the accumulator

Once the affected wheel returns to an acceptable speed, the valves are returned to their normal positions

These actions are repeated until the wheel is no longer in danger of locking up

The valves may cycle as many as 15 times per second

ABS Operation - Brake Pressure Decrease

1

2

3 4

Pump and Motor

Accumulator

Outlet/Dump Valve (Open)

Brake Caliper Inlet/Isolation Valve (Closed) BOO Switch

ABS Operation During Brake Pressure Decrease

Since brake fluid is released each time the outlet/dump valve is opened, there must be a way to replenish thebrake fluid to the system

This is accomplished by using a pump/motor assembly

ABS Operation - Pump/Motor Running

1

2

3 4

Pump and Motor (Running)

Accumulator

Outlet/Dump Valve (Closed)

Brake Caliper Inlet/Isolation Valve (Open) BOO Switch

ABS Operation During Pump and Motor Operation

LESSON ONE-MODULE 1 ADV BRAKE SYSTEM THEORY & OPERATIONTraction Control Operation

Traction Control uses the components of the ABS system to control a vehicle’s wheel spin during acceleration.However, the HCU has an additional Traction Control Inlet/Isolation Valve

On traction Control equipped vehicles the ABS control module monitors the wheel speed sensors to determine ifthe drive wheels have lost traction

If the ABS control module senses wheel spin, it closes the traction control inlet/isolation valve, isolating thehydraulic circuits of the drive wheels from the circuits of the non-drive wheels

The ABS control module then activates the pump and motor assembly to send hydraulic pressure to the brakecircuits of the driving wheels This applies the driving wheels’ brake units, slowing the rotation and maintain-ing traction

The system will continue to cycle until the ABS control module determines that the tires are no longer indanger of losing traction or until the maximum brake application speed limit (usually about 35mph), is

T/C Inlet/Isolation Valve (Open)

Hydraulic Circuit to Non-Drive Wheels

Brake Caliper

Outlet/Dump Valve (Closed)

Inlet/Isolation Valve (Open) BOO Switch

Accumulator Pump and Motor (Running)

2

Traction control operation stops if the brakes are applied.

If used continuously on icy roads, traction control may be shut off by the ABS control module to preventoverheating of the brakes

Some traction control systems reduce the throttle opening, injector pulse width modulation (PWM), and/orretard vehicle timing to control wheel spin This is accomplished through the use of the throttle cable controlrelay or via torque reduction signals sent from the ABS control module to the PCM via the J1850 network

Above a preprogrammed speed (usually about 35mph), only throttle limiting control or torque reduction is theonly system used for traction control Vehicle brakes will not be applied

NOTE: If speed control is operating when traction assist engages, the traction assist system will disengage the

speed control through a speed control relay

Traction Control Operation (continued)

LESSON ONE-MODULE 1 ADV BRAKE SYSTEM THEORY & OPERATION ADVANCE TRAC/ ELECTRONIC STABILITY ASSIST SYSTEM

The purpose of the Advance Trac System is to help the driver maintain the stability and steerability of the vehicle.Advance Trac integrates ABS and TC to further enhance the stability of the vehicle The system shares many ofthe electronic and mechanical elements already present in the TC and ABS system

Note: Service publications and Scan Tools refer to Advance Trac using various terminology It can be called Interactive Vehicle Dynamics (IVD) and/or Electronic Stability Assist Throughout this training course this

system will be referred to as “Advance Trac” and the theory, operation, diagnosis, and service procedures

described apply to any system known by these names

This system constantly monitor the vehicle motion relative to the driver’s intended course

This is done by using a lateral accelerometer to measure lateral (sideways) force and a yaw sensor to measurerotational speed These sensors compare the steering input from the driver with the actual motion of the vehicle

Steering Wheel Rotation Sensor

Active Brake Booster

Stability Assist (ABS) Control Module

Hydraulic Control Unit (HCU)

Wheel Speed Sensor (Active) Wheel Speed Sensor Indicator Sensor Cluster

Traction Control/Advance Trac ON/OFF Switch

1

2

4 6

5

3 8

7

Typical Advance Trac Components

When there is a discrepancy between the driver’s inputs and the vehicle motion, Advance Trac changes theforce at each tire to help control the vehicle.

This is done by applying the brakes in either the ABS or Traction Control mode

Advance Trac will also signal the PCM to reduce engine torque (by retarding engine timing or shutting offfuel injectors) as required

During vehicle operation, if the vehicle begins to rotate excessively left or right, spin out, or slide sideways,the system will attempt to correct the excessive motion

If the vehicle does not respond to steering inputs (based upon inputs from the steering wheel rotation sensor),the system will attempt to increase the turning response of the vehicle

Advance Trac enhances stability during maneuvers that require all available tire traction to control the vehicle Thebenefits of the Advance Trac system are most noticeable when driving in wet/snowy/icy road conditions or whenperforming emergency maneuvers In an emergency lane-change, the driver will experience better overall vehicletraction and have better control of the vehicle

If the driver applies the brakes during a stability control event, the Advance Trac will continue to operate

However, the wheel(s) under the control of the Advance Trac system will be slowed more than those that arebraking, thus continuing to correct the vehicle’s path

When Advance Trac activates, any of the following can occur:

a rumble or grinding sound much like ABS with traction control

a small deceleration or a reduction in the acceleration of the vehicle

the traction control indicator will flash

if the driver’s foot is on the brake pedal, a vibration will be felt in the pedal much like ABS

if the event is severe and the driver’s foot is not on the brake, the solenoid in the active booster will be

energized by the traction control module In the case of a severe event, you may notice brake pedal movement,

a “whoosh” sound and/or a loud vibration from the brake pedal

Some drivers may notice a slight movement of the brake pedal when the Advance Trac system checks itself

The brake pedal moves when an active test of the active brake booster is run

During this test a small amount of pressure will be generated at the master cylinder, but no pressure will begenerated in the brake calipers

This test will occur above 48 km/h (30 mph) after the vehicle has been running approximately 8 minutes

ADVANCE TRAC/ ELECTRONIC STABILITY ASSIST SYSTEM (CONTINUED)

LESSON ONE-MODULE 1 ADV BRAKE SYSTEM THEORY & OPERATION

NOTES

LESSON ONE WORKSTATIONS

LESSON ONE

WORKSTATION 1 ABS/ADVANCE TRAC COMPONENT LOCATION AND FUNCTION

STUDENT ANSWER SHEET

END OF WORKSHEET

COMPONENT FUNCTION COMPONENT NAME TAG

Directions: Read the component functions below and fill in the component name for each in the middle column.

When you are finished, go to the classroom vehicle and locate the ABS, Traction Control, and Advance Traccomponents that perform the functions listed in the left hand column and list the letter/number on the tag attached

to each component in the right column

Allows the driver to disable the Traction Control or

Ad-vance Trac system

Measures vehicle rotational speed as it corners through a

Measures the amount of lateral force on a vehicle

Informs the ABS control module to be prepared to activate

the ABS

Controls Operation of the Anti-lock Brake System

Measures steering wheel rotation direction and speed

In case of a severe stability control event it may cause brake

WORKSTATION 2 WDS UTILIZATION FOR ABS SYSTEMS STUDENT ANSWER SHEET

Directions: Go to the classroom vehicle and use the WDS to view the PIDs listed in the left column of the table

below Write the function of the PID in the center column and list the parameter value displayed (voltage,

resistance, percentage etc.)

PID PID FUNCTION VALUE

What does the # sign indicate?

Test the operation of the hydraulic pump List the buttons that must be pressed to perform this operation

LESSON ONE

WORKSTATION 3 ABS OPERATION STUDENT ANSWER SHEET

Directions: The art below is a schematic of the hydraulic flow of an anti-lock brake system with traction control.

Use this art to answer the questions in this worksheet

1

7

4

3 5

1 List the names of the numbered components in the table below

WORKSHEET CONTINUED ON NEXT PAGE

6

8

WORKSTATION 3 (CONTINUED)

ABS OPERATION STUDENT ANSWER SHEET

2 What is occurring if the brakes are applied and component 5 is open, component 4 is closed and component 8 is

LESSON ONE

1 The standard ABS system function is to:

A Help with a vehicle’s wheel spin during acceleration.

B Help prevent wheel lock up during braking.

C Help enhance stability during maneuvers.

D All of the above.

2 When the brakes are applied hard enough to cause a lockup situation, the ABS module sends signals to the:

A Pump and motor assembly.

B Electronic Control Unit (ECU).

C Wheel speed sensor.

D Hydraulic Control Unit (HCU).

3 During an anti-lock stop, pressure in the hydraulic system is maintained by the:

A Reservoir

B Electronic Control Unit (ECU).

C Pump and motor assembly.

D None of the above.

4 On traction Control equipped vehicles, the ABS control module monitors the wheel speed sensors and willapply the brakes to prevent loss of traction below approximately what speed:

B Adjustment of spark timing

C Fuel injector control

D All of the above

6 What function does the Advance Trac System perform?

A Help control wheel spin during acceleration.

B Help prevent wheel lock up during braking.

C Helps the driver maintain vehicle stability and steerability.

D All of the above.

WORKSTATION 4 ABS OPERATION STUDENT ANSWER SHEET

WORKSHEET CONTINUED ON NEXT PAGE

7 All Hydraulic Control Unit (HCU) solenoid valves are normally open.

A True

B False

8 A customer is concerned because of pulsation in the brake pedal and a clicking sound when braking on slickpavement This is:

A Caused by a bad HCU.

B Caused by a bad master cylinder.

C Caused by a bad ECU.

D A normal condition with most ABS systems.

9 When the opens the pump/motor runs to replenish the brake system

A Inlet/Isolation valve

B Outlet/Dump valve

C Brake caliper

D None of the above

10 The Advance Trac system is active when the vehicle is traveling in reverse

A True

B False

WORKSTATION 4 (CONTINUED)

ABS OPERATION STUDENT ANSWER SHEET

LESSON ONE

WORKSTATION 4 (CONTINUED)

ABS OPERATION STUDENT ANSWER SHEET

END OF WORKSHEET

11 List 3 things which the driver may notice when Advance Trac activates

12 When the Advance Trac system runs a self-test on the active brake booster, what might the driver notice?

13 List the unique components of the Advance Trac System (those in addition to the ABS system)

14 List the components that may be found in the HCU?

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15 List the two other names that the Advance Trac system may be called