Troubleshooting ABS Brakes

Troubleshooting ABS brakes can help you save on repair bills and keep your car safe. An Anti-lock Brake System (ABS) uses a computer to detect and correct skidding conditions while braking. Troubleshooting ABS brakes may require specialized equipment, but there are some simple things to try first.

Troubleshooting Your ABS Brakes

• Go by the book. Don't even consider diagnosing and ABS brake problem without first consulting a service manual for your particular vehicle. Each ABS system has its own configuration, quirks and error codes. The only way to have complete knowledge is with a service manual.
• It's not my fault! Your ABS system only operates when a wheel sensor informs the unit that a wheel is slowing too quickly and may skid. For all other operations, the ABS system is passive. If your brakes are grabbing, soft or squealing, the problem will typically involve the traditional parts of your braking system. While you can still operate the car, you may not have the advantage of the ABS system in the event of an emergency.
• Reboot. Like most computer-controlled devices, your ABS system may throw a false error. If the ABS dash light comes on, turn the car off, wait a moment and then turn the ignition again. This will force the ABS unit to reboot. If the light goes out, you had a bad reading-if it comes back on, you have a problem somewhere in the ABS system.
• Scan me. Your ABS dash light indicates that the onboard computer has logged an error. This error, called a scan code, indicates the location and nature of the problem. The scan code can be retrieved from the computer using a device called a scan tool. An authorized service center can read the scan code for small fee. Your service manual will have a chart to help you read the scan code results.
• Electrical issues. Often, an ABS problem is not an ABS problem at all-it's an electrical issue. Before tackling the ABS components, check a few basic electrical items including: low battery charge, blown fuses, loose or corroded connections and bad electrical grounding. Any of these issues could cause the ABS controller to throw an error.
• I sense a problem. The next thing to check is the connections to the sensors in each wheel. Sometimes the wires will become corroded or break due to debris caught up under the car.
• I don't like your tone. Debris can also be a problem with the wheel speed sensors and tone wheel. The tone wheel is a toothed wheel (either on the brake rotor or wheel assembly that the motion sensor uses to determine wheel speed. Debris or grime on the wheel or between the wheel and the motion sensor can cause an ABS fault.