Component Tests and General Diagnostics

Rear Wheel Antilock Brakes

FAULT CODE CAPACITY
The antilock control module generates and displays flash codes from the ANTILOCK indicator light to help identify the cause of an antilock system fault. The microprocessor memory will store and display only one fault code at a time. Any stored code can be displayed by grounding the service diagnostic connector.

RWAL Electronic Brake Control Module:

The self test feature of the control module is activated whenever the ignition switch is turned to ON or RUN position.
If a system fault is detected, the control module illuminates the ANTILOCK light and stores the fault code in memory. Fault codes are retained in memory even after turning the ignition switch to OFF position.

FAULT CODE IDENTIFICATION
To determine what a fault code is, first turn the ignition key to RUN position. Then momentarily ground the service diagnostic connector and count the number of times the antilock indicator light flashes.

RWAL System Fault Codes:

The initial flash will be a long flash followed by a number of shorter flashes. The long flash indicates the beginning of the fault number sequence and the short flashes are a continuation of that sequence. The long flash must be counted along with the short flashes in order to obtain an accurate fault code count.

*** UPDATED BY TSB # 05-03-90 Mar 26, 1990

If the amber anti-lock warning and red brake lamp illuminates and a Code 4 is present during diagnosis, it may be the result of water contamination of the 4-way connector at the hydraulic valve (located inside the left front frame rail near the front of the vehicle) and/or water contamination in the 50-WAY bulkhead connector. See TSB update for repair procedure.

*** UPDATED BY TSB # 05-01-91 Jan 28, 1991

If the amber anti-lock warning and red brake lamp illuminates and a Code 9 is present during diagnosis, it may be caused by a spread terminal on the 2-way connection for the RWAL speed sensor. See TSB update for repair procedure.

CLEARING A FAULT CODE
To clear a fault code, disconnect the control module connector or battery for a minimum of five seconds. During system retest, wait 30 seconds to be sure the fault code does not reappear.