How do I replace the turn signal switch?
 

So my girlfriend was driving the ole 81 300SD home from work the other night and the headlights went out. I was hoping it was a fuse but it wasn't and then I found here that these switches go bad. At first glance it is not obvious how to remove the steering column cover.

In the meantime while I wait for the a replacement combo switch I am going to just wire up a switch under the hood for the headlights.

If you need to replace the combination switch (high-beam/turn signal/wiper/washer), the steering wheel has to come off. If it's never come off before, it may be hard. The wheel is held on by a pretty large allen screw if I remember correctly and it's hard to stop the wheel from turning as you try to loosen it (the factory put it on tight for obvious reasons).

Once the wheel is off, it's pretty easy to see how the switch comes off, and it's not very hard.

If your problem is that the headlights won't come on, I don't think that has anything to do with the combo switch. I believe there is one fuse for RH and one for LH lights. And there is probably a relay involved. I've never heard of the headlight switch going bad.

The steering wheel needs to be removed for that job.

The cover is held on with two screws......one on each side.......from the back. From memory, they are Torx fasteners..........so be careful........

The wheel itself is held on with one large cap screw. Counter-torque is the problem if you do it by yourself. DO NOT use the steering wheel lock for counter-torque. In fact, make sure the steering lock is released........key in position 1.......prior to putting a socket wrench anywhere near the cap screw.

Once the wheel is off........you'll see how to remove the switch. But, the plug is a bit dicey. It plugs in to a socket behind the cluster. So, the cluster needs to be removed to get at it.

Look here for how to R&R the cluster.
 

Body Electrical:
http://www.peachparts.com/shopforum/diy-links-parts-category/142413-body-electrical.html

Thanks..

I'm allready familiar with removing the cluster.. I still need to get the speedo replaced.. sigh...

As I mentioned in the first post the fuses are good. If I run power from the battery directly to the fuse the lights come on. I found several posts from people with 300SD's with the same problem.

I guess I'll try messing with the switch today and see if I can get it to work before replacing it but I imagine it's a lost cause. I'm short on time so replacing it may cost me less in the long run and GF needs to drive it Tuesday night so .. doing the math.... it makes sense to drop a temporary switch in there until I can make a more permanent repair or replacement.

I guess its a little different than the 123's. They are really easy to take off.

It was pretty hard to get the allen nut out and letting the steering wheel lock itself and a breaker bar helped. Unfortunately here is no notch so you can see where to put the wheel back on?? You don't have to take the cluster out to disconnect the switchs because they are under the dash not behind the cluster.

OK fixed it.. I guess either the contacts were dirty or the connector was loose because now the low beams work.. I think the hi-beams are out because I tried giving them power directly and no go.. it seems odd that they would both go out??

The W123's just use two screws and an electrical plug. 10 minutes R&R. :D

Yep, this is one area where the W123 and the W126 are radically different. The W123 does not require removal of the wheel.......just the switch.

Now you have, my SDL's is bad. Only have low beams and if the switch isn't centered I have no dirver lamp. :rolleyes:

If I could remove that PO stripped allen bolt, I would remove the wheel and replace that switch. I have two of them here. :(

My switch was bad on the SDL........no washers..........my indy said that he never saw a switch go bad due to no washers.........so I spent the better part of a day doing troubleshooting to be absolutely sure it was the switch and nothing else.

Sure enough.......brand new switch...... washers work properly.:D