I have a 2006 Mercedes E350 that the steering wheel controls (both sides) and horn stop working. I checked the fuses with no luck there, can anyone help here ?
I found someone that's shared his experience similar to yours.
At first, by luck I found a genius electrician. He knows which microchips could be replaced by the same ones, and which ones couldn't be. Also, he had some replacement parts despite fact, that he is enthusiast. I went to a meeting in expectation of only having to read any errors, but he began disassemble the steering wheel without switching off the ignition and not disconnecting the battery. :surprise: do not try to repeat it! after disassembling of the steering wheel, he removed triangle pcb under airbag, where are placed horn buttons and some microchips. He tested every chip, everything was OK, so he moved to the next PCB, which is placed under steering column and contacted with connector N80 (take a look at first post). As he explained to me, main problem was in microchip, that provides communication between steering wheel and central processor. He was a bit surprised, because there are different protocols of communication in car, and usually steering wheel doesn't use LEAD protocol to communicate directly with central processor, but this car has got such decision. He tried to find the same microchip at pcb from C-klasse, but it wasn't there. He found this chip in headlight block from w221 and assembled it to my pcb. After he connected everything back, he tried to horn and the sound was heard! After all the manipulations, there was an SRS error, so he connected STAR and reset it. I asked him why did this happen, but he answered, that a such trouble is common among these cars, and there are no opportunities to avoid or prevent it. Total cost: 150$