Test Driving ABS Complaint Vehicles

Most ABS complaint vehicles will require a test drive as part of the diagnostic procedure. A test drive is normally required due to the fact that, ABS trouble codes are erased when the ignition is turned off. The purpose of the test drive is to duplicate the condition and set the ABS code. For this reason, it is important that the ignition not be turned off after the test drive until the ABS trouble codes have been displayed and interpreted.

Before test driving a brake complaint vehicle (especially if the red BRAKE warning lamp 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 lamp may indicate reduced braking ability. The following procedure should be used to test drive complaint vehicles:

1. Turn ignition to the RUN position without starting car and wait until the BRAKE lamp and ANTILOCK DISABLED message turn off. This will allow the pump to charge the accumulator to operating pressure. If the BRAKE lamp and ANTILOCK DISABLED messages do not turn off within 45 seconds, proceed to Step 3.
2. Turn ignition off for 15 seconds.
3. Start Car. Wait for displays to return to normal operating mode before proceeding.
4. With transaxle in PARK, slowly depress brake pedal and release. Be sure to use a full pedal stroke. If the BRAKE warning lamp was previously off but comes on when the pedal is depressed, proceed to Step 6.
5. 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.
6. If at any time during the test drive, the BRAKE lamp comes on and/or the ANTILOCK DISABLED message on the CCDIC appears, enter the ABS "Service Diagnostic Mode" (Accessing and Reading Diagnostic Trouble Codes) and display (and record) any BCM, or ABS trouble codes which have been set. It is important to remember that ABS trouble codes erase when the ignition is turned off. Do not turn ignition off during the test drive.
7. After recording any ABS or BCM codes, return to the ABS Functional Check and proceed with the appropriate diagnostic tests as directed by the procedure. If no codes are present, you should also return to the Functional Check.