Initial Inspection and Diagnostic Overview

PRELIMINARY CHECKS
Diagnosis of the Anti-Lock Brake system should begin with a visual check of the components for leaks, loose connectors or damage. After the visual inspection, check for fault codes stored in the Anti-Lock Brake System ECU (Z108). Reading and Clearing Diagnostic Trouble Codes

If a fault code or codes are stored, record the codes and then proceed to Fault Code Chart. Manufacturer Code Charts

If no codes are stored, proceed to the Diagnosis By Symptom. Symptom Related Diagnostic Procedures


If a fault has occurred, or has been identified by the electronic control unit (ECU) self diagnostic function and the ABS warning light is illuminated, the system and components must be checked to locate and rectify the fault, enabling the faulty component or harness to be replaced.

NOTE: If the warning lamp has indicated a fault in the system, and no fault code has been stored in the memory, the cause of the fault could be:
a) Failure in electrical supply
b) Loss of hydraulic pressure
c) Faulty pressure switch
d) Bad ECU ground
e) Faulty warning light relay
f) System not fully charged before driving away
g) ECU not connected

Before commencing the fault diagnosis procedure the following items must be checked:
- Inspect all exposed cables for damage or abrasion.
- Check grounds on ABS system.
- Battery - state of charge.
- Fluid level in reservoir.
- All ABS fuses and electrical connections.
- Check hub end-float.

Fault rectification
1. The complete harness must be replaced if faults are found in the wiring harness.
2. DO NOT use unspecified cables or connectors, as this could jeopardize the safe function of the ABS.
3. DO NOT attempt to open the sealed 35 way connector to ECU.

Recommended equipment
Wabco diagnostic controller - 446 300 300 0

NOTE:
- After any steering adjustment, bearing replacement/adjustment, brake disc replacement, check hub end-float and sensor clearance.
- Having fixed faults, clear ALL memory codes and road test vehicle.