Component Tests and General Diagnostics
INSPECTION AND ROAD TEST1. Visually inspect the ABS for damaged or disconnected components and connectors.
2. Verify the brake lamps are operational. If they are not, repair them prior to continuing.
3. Connect the DRBIII scan tool to the Data Link Connector located under the instrument panel to the right of the steering column. If the DRBIII does not power-up, check the power and ground supplies to the connector.
4. Turn the ignition key to the ON position. Select ANTILOCK BRAKES.
5. Read and record any Diagnostic Trouble Codes (DTCs). If any DTCs are present, refer to the appropriate chassis diagnostic information.
NOTE: Diagnostic trouble codes (DTCs) are kept in the controller's memory until either erased by the technician using the DRBIII, or erased automatically after 3500 miles. DTCs are retained by the controller even if the ignition is turned off or the battery is disconnected. More than one DTC can be stored at a time. When accessed, the number of occurrences and the DTC that is stored are displayed.
If no problems are observed, it will be necessary to road test the vehicle.
Many ABS conditions judged to be a problem by the driver may be normal operating conditions. See Antilock Brake System - Operation to become familiarized with the normal characteristics of this antilock brake system.
WARNING: CONDITIONS THAT RESULT IN TURNING ON THE RED BRAKE WARNING INDICATOR LAMP MAY INDICATE REDUCED BRAKING ABILITY.
Before road testing a brake complaint vehicle, note whether the red BRAKE warning indicator lamp, amber ABS warning indicator lamp, or both are turned on.
If it is the red BRAKE warning indicator, there is a brake hydraulic problem that must be corrected before driving the vehicle. Refer to the Base Brake System - Diagnosis And Testing. If the MIC determines the amber ABS warning indicator is not functioning, it will illuminate the red BRAKE warning indicator.
If the amber ABS warning indicator is on, road test the vehicle as described below. While the amber ABS warning indicator is on, the ABS is not functional. The ability to stop the car using the base brake system should not be affected.
If both the red BRAKE and the amber ABS warning indicators are illuminated, there is possibility that there is an ABS problem. For some failures the ABS unit will discontinue ABS as well as EVBP and illuminate both the red BRAKE and the amber ABS warning indicators. Braking ability may be reduced. Before road testing, read DTC's and refer to the Appropriate Diagnostic Information. Also, the MIC will illuminate both the red BRAKE and the amber ABS warning indicators if the ABS CAB is not communicating on the BUS.
6. Turn the key to the OFF position and then back to the ON position. Note whether the amber ABS warning lamp continues to stay on.
7. If the amber ABS warning indicator lamp stays on, shift into gear and drive the car to a speed of approximately 25 km/h (15 mph) to complete the ABS Start-Up and Drive-Off Cycles (see Antilock Brake System - Operation). If at this time the amber ABS warning indicator lamp stays on, refer to the Appropriate Diagnostic Information.
8. If the amber ABS warning indicator lamp goes out at any time, drive the vehicle a short distance. Accelerate the vehicle to a speed of at least 64 km/h (40 mph). Bring the vehicle to a complete stop, braking hard enough to cause the ABS to cycle. Repeat this action several times. Using the DRBIII, read and record any Diagnostic Trouble Codes (DTCs). If any DTCs are present, refer to the Appropriate Diagnostic Information.