ABS Vehicle Test Drive

Most ABS complaints will require a test drive to properly duplicate and diagnose the condition.

WARNING: CONDITIONS THAT RESULT IN TURNING ON THE RED BRAKE WARNING LAMP MAY INDICATE REDUCED BRAKING ABILITY.

Before test driving a brake complaint vehicle, note whether the red BRAKE warning lamp, amber ABS warning lamp, or both are turned on. If it is the red BRAKE warning lamp, there is a brake hydraulic problem that must be corrected before driving the vehicle. Refer to the BASE BRAKE SYSTEM for diagnosis of the red BRAKE warning lamp. If the red brake warning lamp is illuminated, there is also a possibility that there is an ABS problem and the amber ABS warning lamp is not able to illuminate, so the CAB turns on the red Brake warning lamp by default.
If the amber ABS warning lamp is on, test drive the vehicle as described below. While the amber ABS warning lamp is on, the ABS is not functional. The ability to stop the car using the base brake system should not be affected.
If a functional problem of the ABS is determined while test driving the vehicle.
1. 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.
2. If the amber ABS warning lamp goes out, shift into gear and drive the car to a speed of 25 kph (15 mph) to complete the ABS start-up and drive-off cycles (see ABS ELECTRONIC DIAGNOSIS).
3. If the amber ABS warning lamp remains out, drive the vehicle a short distance. Accelerate the vehicle to a speed of at least 40 mph. Bring the vehicle to a complete stop, braking hard enough to cause the ABS to cycle. Again accelerate the vehicle past 25 mph.