PeachParts Mercedes-Benz Forum - View Single Post

CBGraves · #1 10-21-2003, 10:37 PM

I replaced my combination switch on by 300SDL this weekend and thought I would share the experience. My repair CD lacked some detail.

First step is to disconnect your battery ground to disable the airbag. Remove airbag from steering wheel by loosening the T30 torx screws from both side of the back of the steering wheel. The screws will not come out of the steering wheel completely. lift the airback out and pull the electrical plug from the airbag.

With the airbag removed, the steering wheel bolt will be revealed. It requires a 10mm hex bit. Here is where the fun begins. The bolt is glued in and its a bear to take out. Speaking now from experience, the bolt is VERY easy to strip. I used a 2' long ratchet. My first attempt I striped the bolt almost completely. When removed properly, the bolt will break loose sounding like a rifle shot. It WILL NOT "give" gradually. If you feel it give, than its the head stripping. STOP. I took my hex bit and ground the chamfer off to leave sharp edges around the end of the bit so that it would fit down into the head of the bolt as far as possible. Then I tapped it down into the bolt head. I hit it several times with an impact wrench which did nothing. I went back to the ratchet and finally got the bolt to break loose without stripping the head any worse. Turn the ignition key far enough to disengage the steering lock. You don't want to apply this much force against it. My technique was to put my left foot into the car, right foot on the ground, pull up on the steering wheel with left arm and apply downward (CCW) force on the rachet with right arm. Get someone to help you if possible.

With the bolt out, my steering wheel came right off (mark the location of the wheel relative to the steering shaft by marking it). I was prepared for round two, but it really was no contest. If my experience is any indication you will not need a wheel puller. Then I took out the three small screws that hold on the coverplate under the steering wheel. This reveals the cruise control and combination switch. Three screws hold the assembly in the steering shaft. Remove the screws and take note of the routing of the wiring harness for the cruise control, etc. There are two spring-loaded contacts embedded into the combination switch. Pull them out and insert them into the new switch. Pull the combination switch out of the steering column and remove the cruise control switch by sliding it out of its mounting location in the combination switch assembly. The cruise control wiring harness is held onto the bottom edge of the combination switch assembly by a clip. To remove the clip, use needle nose pliers and squeeze the locking tabs together from the back side of the combination switch assembly while pulling out on the clip. This can be a little tricky since it is hard to reach with the wiring harness still attached under the dash. I managed to do the whole job without disconnecting the cruise control harness.

Now the only thing holding the combination switch to the car is the wiring harness. Its connector is under the dash just to the outer side of the steering column. Remove the lower panel and you will be able to barely see it through the opening between the dash and the corregated air plenum. I put a flat screwdriver thru the opening and pried the connector partially loose. Then I pulled the instrument cluster and reached into the dash and pulled the connector off. Then you can pull the combination switch out snaking the wiring harness out through the steering column.

Assembly is the reverse of removal. The assembly was easy.

I now have my high-beams back!!