Initial Inspection and Diagnostic Overview

INSPECTION AND VERIFICATION
1. Verify the customer's concern by operating the vehicle and applying the brakes under different conditions to duplicate the condition.
2. Check for applicable TSB's.
3. Perform following visual inspection to determine if one of the following mechanical or electrical concerns apply:

Mechanical
- Parking brake cable binding.
- Improperly inflated tires.
- Mismatched wheels or tires.

Electrical
- Blown fuse 13(40A) -Power Distribution Box.
- Blown fuse 18(30A) -Power Distribution Box.
- Blown Fuse 9 (10A) -Fuse junction panel.
- Blown Fuse 28(15A) -Fuse junction panel.
- Blown Fuse 12 (5A) -Fuse junction panel.
- Damaged connections.
- Disconnected connectors.

4. If inspection reveals an obvious concern that is readily serviced, correct the concern before continuing with Inspection and Verification.

DATA LINK DIAGNOSTICS - The ABS module communicates with the data link connector (DLC) located beneath the instrument panel. Rotunda New Generation Star (NGS) Tester 007-00500 or equivalent scan tool is needed to access ABS diagnostic trouble codes (DTC). Rotunda Service Bay Diagnostic System (SBDS(r)) 001-00001 may also be used instead of the NGS to diagnose this system.

NOTE: Refer to the scan tool operators manual for information on performing tests or clearing codes.

1. If the concern remains after visual inspection, connect the scan tool to the data link connector (DLC) located beneath the instrument panel
2. Select and perform "DATA LINK DIAGNOSTICS" test.
3. If the scan tool responds with "NO RESPONSE/NOT EQUIPPED" for the anti-lock brake control module, Go to Pinpoint Test E. E
4. If the DATA LINK DIAGNOSTICS test is passed for the anti-lock brake control module, retrieve continuous 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 the Diagnosis by Symptom to continue diagnostics. Symptom Related Diagnostic Procedures
6. If DTCs are retrieved, Go to the 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 scan tool, Go to Pinpoint Test E. E

WARNING LAMP INDICATORS - The brake system uses two warning indicators to alert the driver of malfunctions in the system.
The red BRAKE warning indicator will come on for only two reasons:
- If the brake fluid level in the brake master cylinder reservoir falls below the level which is determined by the switch point of the fluid level switch.
- If the parking brake is applied.
The amber ANTI-LOCK BRAKE warning indicator will come on to indicate numerous concerns:
- It warns the driver that the anti-lock brake system has been turned off due to a condition that exists in the system.
- Normal power-assisted braking remains while the amber ANTI-LOCK BRAKE indicator is on but the wheels can lock during a panic stop.
- The anti-lock brake control module monitors system operation and can store all defined DTC's in its keep-alive random access memory.
- Certain procedures must be followed to find the fault in this situation. They are explained in this section.

IMPORTANT INFORMATION

Caution: Following the wrong sequence or bypassing diagnostic steps will lead to unnecessary replacement of parts and/or incorrect resolution of the symptom.

Follow the diagnostic procedures step-by-step in order as indicated within the diagnostic tests.
- The anti-lock brake control module CANNOT recognize some failures; therefore if a concern exists and no DTCs are stored by the anti-lock brake control module, other diagnostic steps must be followed.
- The anti-lock brake control module cannot store a DTC if it is not supplied battery positive voltage (B+). This condition can be found by using the Quick Test Check Sheet. Quick Tests

TEST EQUIPMENT
The following equipment is recommended for diagnosing anti-lock brake system:
- Rotunda Anti-Lock Breakout Box Adapter 007-00116 or equivalent.
- Rotunda EEC-IV 60-Pin Breakout Box 014-00322 or equivalent.
- Rotunda New Generation Star (NGS) Tester 007-00500 or equivalent.
- Rotunda Service Bay Diagnostic System (SBDS(r)) 001-00001 may also be used instead of the NGS to diagnose this system.
- Rotunda 73 Digital Multimeter 105-R0051 or equivalent.