Anti-lock brake systems release brake fluid pressure if your tires begin to skid.
Anti-lock brake systems are standard in most modern vehicles. They allow a tire to continue to turn a bit to prevent skidding if you hit the brakes and the vehicle does not stop immediately. There is usually a light on your dashboard that will illuminate to indicate a problem with this system. If this light turns on, there are a number of things you can do to try to diagnose the problem yourself.
1. Turn your vehicle off. Wait one minute, then start it back up. The ABS computer does a self-diagnostic every time you turn the ignition.
2. Observe the ABS warning light. If it is still illuminated, go to Step 3.
3. Locate the fuse panel for your vehicle with the service manual. It is generally under the hood or under the dashboard.
4. Open the fuse panel and observe the ABS fuse. Replace if necessary. If you replaced the fuse, repeat steps 1 and 2. If the fuse was in working order, replace the fuse panel cover and go to Step 5.
5. Locate the ABS controller using the service manual.
6. Remove the main connector from the ABS controller. Observe the condition of each. Look for corrosion or debris that may be blocking the signal. Spray each with aerosol contact cleaner.
7. Test each wire connector with the multimeter and compare the readings with the standards found in your service manual. If any readings are low, you may need to replace that wire or the entire ABS controller. If you do not have a multimeter, skip this step.
8. Reinsert the main connector into its spot on the ABS controller.
9. Raise the car with a jack far enough for you to inspect the wheel wells.
10. Locate the wheel speed sensor. Observe its condition. Loose or missing wires will need to be replaced.
11. Repeat steps 1 and 2. If the ABS light is still on, contact a shop that has an ABS scan tool. This will cost generally between $50 and $100 but will provide you with a code that will tell you exactly what is wrong with the ABS.