Service brake malfuntion light
SOURCE: Mercedes Bens E240 has a service brake malfunction
The service brake uses brake shoes that are within the rear wheel hubs and make no use of the brake pads and rotors. The service brake should be on maximum on the 6th click. There are two points of adjustment. The easiest and most usual is the service brake cable adjustment in the middle of the car, I confess I draw blank here but I think there is an access panel under the rear seat (as per the C class) that permits handbrake cable adjustment without having to do it from under the car. If the service brake cannot be adjusted enough at the handbrake coupling then the each rear hub will need adjusting. First slacken the hand brake coupling - this will allow greater adjustment in future when the shoes have been adjusted. Start with the Left rear wheel. Remove one wheel nut only but leave the wheel on and jack up the car at the back left until the left wheel is free to rotate. Position the empty wheel nut hole at the 1 o'clock position and shine a powerful torch into the hole. Towards the top edge of the hole you should see the toothed edge of the service brake adjustment wheel - you may have to rotate the road wheel backwards and forwards a few degrees to locate it. Insert a screw driver and click the adjustment teeth upwards, one tooth at a time. Keep doing this until the road wheel rotation is stiff, then take about 5 clicks downwards to release the brake shoe contact. Lower the car, put back the removed wheel nut and tighten. Remove a wheel nut from the right road wheel and lift the car until it can freely rotate. Position the nut hole at about 11 O'clock until you can see the adjustment teeth. This time the teeth need to be clicked downwards (note this important difference) until the rotation is hindered. Then click upwards for 5 teeth to release the shoes. When both sides have been adjusted the remaining fine adjustment can be done with the service brake cable adjustment in the middle of the car. The brake should begin to come on at about 3 clicks and be very stiff at 6 clicks with almost all your effort to get to 7 clicks. Unless you drive around with service brake left on the shoes, with occasional adjustment, should last the life of a car. If no amount of adjustment sorts out the service brake the shoes may need replacing and I would leave this to the Mercedes guys as the job is a bit of pain.
What does this mean? When is the code detected?
. Take the car to a local auto parts store and ask them to use their OBD2 scanner to read the trouble code. Once they do that, they will look up the code description and give you ideas on how to make the repairs. It is usually a free service of the auto parts store
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