Technical information

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Technician Guidelines for Antilock Braking Systems
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TABLE OF CONTENTS
I. AN INTRODUCTION TO ANTILOCK BRAKING............ 3
A. What is an ABS? ............................................... 3
B. How Do ABSs Work?......................................... 5
C. How Should I Drive an ABS-equipped Vehicle
During Road Tests? ........................................... 6
D. What Are the Features and Benefits of ABSs? ..... 7
II. ABS COMPONENT DESCRIPTIONS AND
OPERATION ......................................................... 8
A. Electronic Control Unit (ECU)............................. 8
B. Modulator Valves............................................ 10
C. Wheel Speed Sensors ...................................... 11
D. ABS Malfunction Indicator Lamps..................... 12
E. ABS Diagnostics .............................................. 12
F. Traction Control Systems ................................. 13
III. ABS TROUBLESHOOTING, MAINTENANCE AND
INSPECTION ....................................................... 14
A. ABS Troubleshooting ...................................... 14
1. General Diagnostic Principles ..................... 14
2. Notes on Electrical/Electronic Connections.. 19
3. Error Detection Methods............................ 23
4. Causes of Common ABS Sensor Problems .... 25
B. ABS Maintenance and Inspection..................... 27
1. ABS Sensor Pickup Adjustment ................... 27
2. ABS Sensor Pickup Removal and Installation 27
3. Sensor Pickup Removal—Front Axle ............ 27
4. Sensor Pickup Installation—Front Axle ........ 27
5. Sensor Pickup Removal—Rear Axle ............. 28
6. Sensor Pickup Installation—Rear Axle ......... 28
7. Proper ABS Sensor Resistance..................... 29
8. Modulator Valves/Routine Inspection.......... 29
9. Modulator Valve Removal and Installation .. 30
10. Proper ABS Modulator Valve Resistance .... 30
IV. ABS SPEC’ING CONSIDERATIONS ......................... 31
V. GLOSSARY OF ABS TERMS ................................... 33
VI. INDEX................................................................ 42