Test Driving ABS Complaint Vehicles

Some ABS complaint vehicles will require a test drive as a part of the diagnostic procedure. A test drive may be required due to the fact that some ABS codes will not set unless the vehicle is moving. The purpose of the test drive is to duplicate the customer complaint condition and set a current ABS trouble code.

Important: Before test driving a brake complaint vehicle (especially if the red BRAKE warning light is illuminated), test the brakes at low speed to be sure that the car will stop normally. Remember that conditions which result in illumination of the red BRAKE warning light may indicate reduced braking ability. Refer to diagnosis when the BRAKE light is illuminated. The following procedure should be used to test drive ABS complaint vehicles.

1. Ignition 'ON' Turn ignition to the RUN position without starting car and wait until the ANTI-LOCK light turns off. If the ANTI-LOCK light does not turn off the ABS is disabled, note that the light did not turn off and proceed to step 2.
2. Start Car.
3. Drive vehicle a short distance. During this test drive, be sure that the vehicle achieves at least 20 miles per hour. Brake to at least one complete stop and accelerate slowly to a minimum speed of 20 mph.
4. If at any time during the test drive, the ANTI-LOCK light comes on, enter 'ABS Diagnostic Mode' and display (and record) any ABS trouble codes which have been set using blink codes or the TECH 1. If no codes are set, or the ANTI-LOCK light never comes on, carefully note any unusual symptoms demonstrated by the system.
5. After recording any trouble codes which appear, or noting unusual vehicle symptoms, return to the ABS Functional Check and proceed with the appropriate diagnostic tests as directed by the procedure.