Initial Inspection and Diagnostic Overview

INSPECTION AND VERIFICATION
1. Verify the concern by operating the vehicle and applying the brakes under different conditions to duplicate the condition.
2. Check for applicable Technical Service Bulletins (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 4 (60A) - Power Distribution Box.
- Blown Fuse 5 (10A) - Fuse junction panel.
- Blown Fuse 32 (15A) - Fuse junction panel.
- Damaged connectors.
- Disconnected connectors.

4. If inspection reveals an obvious concern that is readily serviced, correct the concern before continuing with Inspection and Verification.
5. If no scan tool is available, review Warning Lamp Indicators below and the proceed to Quick Test. Quick Tests

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 DTCs 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.

DATA LINK DIAGNOSTICS
The ABS module communicates with the data link connector (DLC) located beneath the instrument panel. Rotunda New Generation Star (NGS) Tester or equivalent scan tool is needed to access ABS diagnostic trouble codes (DTC). Rotunda Service Bay Diagnostic System (SBDS(r)) 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 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 S. S No Communication With ABS Control Module
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 S. S No Communication With ABS Control Module

TEST EQUIPMENT
The following equipment is recommended for diagnosing anti-lock brake system:
- Rotunda Anti-Lock Breakout Box Adapter or equivalent.
- Rotunda EEC-IV 60-Pin Breakout Box or equivalent.
- Rotunda NGS Tester or equivalent.
- Rotunda SSBDS(r) may also be used instead of the NGS to diagnose this system.
- Rotunda 73 Digital Multimeter or equivalent.