ABS Brake System Malfunction - ABS Light On

Some simple maintenance could help to solve the problem

An ABS brake warning light coming on is annoying. It becomes frustration when you can't find the source of the problem. As with any problem that can not be easily diagnosed always start with the simple things first. This applies to most models from 1985 to 1995 with ABS brakes. If you are having problems with finicky brake pulsations or your ABS light is coming on, there is one simple thing you should do first.

Play Video

Problem & Solution

Common among these chassis:

R107
W124
W126
R129
W140
W201

Start by removing and cleaning your ABS brake sensors. As you can see in these pictures you might be surprised to discover just how dirty they can get. One the front sensors this is usually caused by brake pad dust collecting over a long period of time. Most cars have three sensors. One each on the front wheels located on the front side of the brake hub. One in the rear mounted to the forward section of the differential housing.

Remove the two bolts and the sensor pulls straight out. Do not use compressed air when cleaning. Breathing fine particle brake pad dust is hazardous to your health. Get a large pan of hot soapy water and place it directly under the area you are cleaning. Use a brush to splash the hot water up on the sensor and mounting hole and scrub thoroughly. Then use a small cup to pour hot water over the entire area to rinse. Let it air dry. Always use thread locking compound when re-installing the brake sensor bolts.

If this does not solve your problems then you might consider taking your car into a brake shop that really understands ABS brake systems. You may need new sensors and wires, but since they are expensive you want to make sure they are the problem.