 | Jeff Lovell is the owner of Neptune Radiator and Auto Repair. He started a radiator repair shop in 1996 and has grown over the last 15 years into an automotive repair shop. With 3 ASE Certified technicians including 1 Master ASE Certified technician, they have over 40 years of combined experience. They do everything except glass and body repair. For more information please contact us at 620.231.5890 or visit us at 902 West 4th Street. |
Automotive Service & Repair
2012-02-28 10:17:01
What is wrong with my ABS?
Q: My Anti-lock brake system lights just came on. Can you tell me what might be the problem? Is it a cause of concern?
A: Never ignore any warning light on your car. They were developed for your safety and prompt attention keeps you safe as well as prolongs the life of your vehicle.
Your Anti-Lock Brake System, or ABS, works by keeping your wheels from skidding while you slow down. The built in speed sensors located at each wheel provide the information needed to control the pump and valves, which add and release the appropriate amount of pressure. The light is an indication that there is a disruption in the system and it is not receiving the information it needs to work properly.
When a wheel speed sensor (WSS) fails or there is a problem in the sensor’s wiring circuit, it disables the ABS system and the ABS warning light comes on. Loss of a wheel speed signal is a serious problem because the ABS module needs accurate input from all its sensors to determine whether a wheel is locking up. Without this information, the ABS system can’t its job.
One of the most common reasons for an activated ABS light is an air gap inducing a strong signal in the sensor’s magnetic windings. Variations in the air gap can also cause fluctuations in the sensor’s output signal. Bad wheel bearings or missing, broken, or chipped teeth on a tone ring may cause this issue. Even minor damage to the tone ring that’s nearly impossible to see can sometimes cause a problem.
If you suspect a problem, you can measure the output voltage. Plug a breakout box into the ABS module’s wiring harness and attach the leads from the digital volt ohm meter to the appropriate pins on the WSS circuit. Refer to a shop manual for the exact voltage specifications for your vehicle.
I also suggest a scope check. While this is not something you can do at home, a dynamic check of the system is the best way to analyze and then solve the problem. When in doubt, talk to a professional.
