Self-Diagnostic Procedures

The ABS system has a self diagnostic capability which can be used to assist in isolation of ABS faults. This feature includes 16 fault codes which may be displayed by the ABCM through flashing of the red BRAKE warning lamp. Only one fault code can be stored at a time. Any codes that may have been present are lost when the ignition is turned off. It may be necessary to test drive the vehicle to duplicate the condition and set the Fault Code (See TEST DRIVING VEHICLE). In order to access the ABS Fault Codes, enter ABS diagnostic mode as described below.

The following information is to be used for reference when directed by the appropriate diagnostic procedure. Do not attempt to diagnose an ABS condition starting here.
1. Turn ignition to ON. Remember that fault codes are erased when the ignition is turned off.
2. Release parking brake. Check to see that parking brake is not causing the BRAKE warning lamp to illuminate. Otherwise, disconnect the parking brake switch at the parking brake pedal.
3. Check to see that a fault has been detected. Either the BRAKE warning lamp or the ANTI-LOCK warning lamp should be illuminated. If not, verify complaint by test driving vehicle. Proceed slowly, checking the operation of the service brakes.
4. Once a fault is detected, without turning off the ignition, depress brake pedal fully with firm pedal effort.
5. If a fault code is present, after about 5 seconds, the red BRAKE warning lamp will begin to flash. Count the number of times the BRAKE warning lamp flashes. Lamp flashes should be interpreted as follows:
a. The number of times that the lamp flashes represents the number of the fault code.
b. If the lamp does not come on at all, crank the engine to perform a BRAKE warning lamp bulb check. If the lamp does not light, repair the BRAKE warning lamp as required. If the lamp does light, no fault codes are present. Attempt to reverify the complain or use symptom diagnosis methods as directed by appropriate diagnostic procedures.
c. If the BRAKE warning lamp stays on continuously during the diagnostic procedure, see DIAGNOSIS BY SYMPTOM information as directed by the FUNCTIONAL CHECK.

To exit ABS Diagnostic Service Mode, simply release the brake pedal. When the BRAKE warning lamp begins to flash, the brake pedal may be released. If the brake pedal is held down continuously, the fault code will repeat in about 10 seconds.