Initial Inspection and Diagnostic Overview

WARNING LAMP INDICATORS - The anti-lock brake system uses two warning indicators (BRAKE and ABS) to alert the driver of concerns in the system.

- The BRAKE warning indicator will come on for only two reasons:
1. If the brake fluid level in the brake master cylinder reservoir falls below the level which is determined by the set point of the fluid level switch.
2. If the parking brake is applied.

- The amber ABS warning indicator will come on for numerous reasons. It warns the driver that the ABS and traction control have been turned off due to a symptom that exists in the system. Normal power-assisted braking remains but the wheels can lock during a panic stop while the indicator is "ON".

NOTE:
- Normal anti-lock brake system warning lamp sequence: Amber light will come on for 2-3 seconds during self-check when ignition switch is in the "RUN" position.
- Follow the diagnostic procedures step-by-step in order as indicated. Otherwise improper diagnosis will be made.

- For certain fault codes, even if the fault has been fixed the ABS light will stay "ON" after a key "OFF"/"ON" cycle until the speed vehicle reaches about 10 km/h (6 mph) and will then go "OFF" if the fault has disappeared. As a consequence, always erase the memory after having performed any repair procedure and before verifying the effectiveness of this repair by looking at the lamp status. Otherwise, if the memory is not erased the light will stay "ON" after a key "ON" cycle (until the car reaches a speed up to 6 mph) even if the fault has been corrected.

PINPOINT TESTS
- Do not perform any of the pinpoint tests unless you are so instructed. Each pinpoint test assumes that a fault has been detected in the system with direction to enter a specific diagnostic routine. Performing any pinpoint test without direction may produce incorrect results and replacement of working components. Correct test results are dependent on the proper operation of related components/systems. It may be necessary to correct any concerns in these areas before passing the test.
- Do not replace any parts unless the test results indicate they should be replaced.
- When more than one diagnostic trouble code (DTC) is received, always start with the first DTC received.
- Do not measure voltage or resistance at the anti-lock brake control module unless otherwise specified.
- Use the Breakout Box Chart to identify proper circuits and pins. Control Module Pinout Values
- To ensure correct pinpoint test procedures, follow steps in order as listed. Follow each step until a fault is found.
- After completing any service to the anti-lock brake system, verify all components are properly reconnected, then clear all DTCs. Refer to Diagnostic Trouble Code, Erasing. Clearing Trouble Codes

INSPECTION AND VERIFICATION
1. Verify the customer's original concern by operating the anti-lock brakes and traction control system (if equipped) to duplicate the condition.
2. Visually inspect to determine if one of the following mechanical or electrical concerns apply:
Mechanical:
- Low brake fluid
- Damage front or rear anti-lock brake sensor.
- Damage front or rear anti-lock sensor indicator.
- Damaged brake lines.
- Damaged wheel bearings.
- Parking brake binding
- Improperly inflated tires.
- Mismatched wheels or tires on vehicle.
Electrical:
- Blown Fuses:
- 60A ABS Fuse 3
- 30A ABS Fuse 7
- 7.5A Fuse 22
- 7.5A Fuse 30
- Burned out anti-lock indicator lamp.
- Burned out traction control indicator lamp.
- Damaged connectors.
- Disconnected connectors.
- Corroded connectors.
3. If the inspection reveals an obvious concern that is readily serviced, correct the concern and retest before continuing.
4. If a concern remains after the inspection connect the Rotunda New Generation Star (NGS) Tester or equivalent to the data link connector (DLC) located beneath the instrument panel to perform Data Link Diagnostics test. If the Data Link Diagnostics test is passed for the anti-lock brake control module, retrieve continuous Diagnostic Trouble Codes (DTCs) and execute self test diagnostics for the anti-lock brake control module to retrieve current DTCs.
5. If self test is passed and no DTCs are retrieved go to Diagnosis By Symptom to continue diagnosis.
6. If DTCs are retrieved, go to Anti-Lock Brake Control Module Diagnostic Trouble Code (DTC) Index to continue diagnostics. Diagnostic Trouble Code Descriptions
7. If the anti-lock brake control module cannot be accessed by the NGS, go to Pinpoint Test A.
8. If the scan tool responds with NO RESPONSE/NOT EQUIPPED for the anti-lock brake module, go to Pinpoint Test A.

NOTE: Rotunda Service Bay Diagnostic System (SBDS) or equivalent may also be used to diagnose this system. Refer To Tools and Equipment for more information.