Diagnosis And Testing - Inspection And Road Test
- Visually inspect the Antilock Brake System (ABS) for damaged or disconnected components and connectors.
- Verify the brake lamps are operational. If they are not, repair them prior to continuing.
- Connect a scan tool to the Data Link Connector (DLC) located under the instrument panel to the left of the steering column. If the scan tool does not power-up, check the power and ground supplies to the connector.
- Turn the ignition key to the ON position.
- Using the scan tool, read and record any Diagnostic Trouble Codes (DTCs). If any DTCs are present, refer to the appropriate diagnostic information.
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. To become familiarized with the normal operating characteristics of this antilock brake system, refer to OPERATION .
WARNING:Conditions that result in turning on the red brake warning indicator lamp may indicate reduced braking ability.
Before road testing the 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 lamp, there is a brake hydraulic problem that must be corrected before driving the vehicle
Refer to RED BRAKE WARNING INDICATOR .
The following conditions will cause the red BRAKE lamp to illuminate:
- Low fluid in the brake reservoir
- Park brake engaged
- Brake hydraulic problem
- ABS issue that will not allow the brake proportioning function
- If the amber ABS warning indicator is on, road test the vehicle as described below. While only the amber ABS warning indicator is on, the ABS is not functional. The ability to stop the vehicle using the base brake system should not be affected.
- Turn the key to the OFF position and then back to the ON position. Note whether the amber ABS warning indicator lamp continues to stay on.
- If the amber ABS warning indicator lamp stays on, shift into gear and drive the vehicle to a speed of approximately 25 km/h (15 mph) to complete the ABS Start-Up and Drive-Off Cycles. Refer to OPERATION . If at this time the amber ABS warning indicator lamp stays on, refer to the appropriate diagnostic information.
- 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 scan tool, read and record any (DTCs). If any DTCs are present, refer to the appropriate diagnostic information.