An automobile's Anti-lock Braking System or ABS is equipped to allow the driver control over the vehicle's direction while braking. If the brakes lock in one direction while braking in an emergency situation, it could be hazardous for both the driver and his passengers. Allowing the vehicle to steer a little more while braking could enable the driver to steer clear of a more serious accident. If the vehicle stops a little further along than usual or the brakes feel soft and do not brake as hard as they used to, then you will have to bleed your ABS brakes. Bleeding the brake system requires removing the air that has managed to get trapped inside, and this is usually done by pumping fluid into the brake system.
- Find where the bleed valve is located. For this procedure you may need to raise your car and take the wheels off to expose the bleed valve. You may raise the vehicle on blocks with a jack and add proper support underneath the car to avoid serious injuries. Find the bleeder valve, which is usually behind the brake system, and is a bolt on a spout-like object. Find the right wrench to turn or loosen the bolt, but do not open it completely, leave it closed; we just need this to be loosened a bit. Do this for all four wheels.
- Clean out the master cylinder reservoir. Go under the hood and locate the master cylinder reservoir and empty out the old fluid contained in it. You will need something to suck out all the fluid, like a turkey baster. Suck out as much of the old fluid as you can, and clear the reservoir of the dirt and sediments that have collected there over time. You can use a clean rag that is lint free to make sure you get all the dirt out. Fill the master cylinder reservoir with clean and new brake fluid, and make sure to refill it for the whole bleeding process. Never let the fluid level go below the halfway mark.
- Connect tubing on bleeder. Find a plastic tube that would fit snugly on the bleeder bolt and long enough to put the other end in a clear jar. Fill the jar with an inch or two of brake fluid so no air is allowed into the tubes and the brake cylinder.
- Have an assistant place pressure on the brake pedal. Having an assistant will be useful for this procedure, because you'll need another person applying pressure on the brake pedal. Tell your assistant to put just the right amount of pressure on the brake pedal and keep it down until you give the signal to release. When pressure is applied open the bolt about a quarter, then you'll notice the old fluid left inside will leak out into the jar. When the leak stops, close the bolt and ask your assistant to release pressure off the brake pedal. The process continues until clear fluid is seen passing through the plastic tube.
This process of bleeding the ABS brakes should be done for all four wheels. Usually air gets into the brake system whenever repairs or changes are made to the brake cylinder or caliper.