W124 Ignition Switch - Take Apart and Repair?
 

Has anyone ever taken apart and repaired the ignition switch (electrical part only) on a 1987 300D Turbo (W124, OM603) or similar vehicle? I'm starting to have occasional electrical problems and so far it looks like everything affected is on circuit 15R of the ignition switch.

A slightly burned switch contact is easily repairable if I can take the switch apart. I was able to do exactly that on my 1996 E300D (W210, OM606NA). Of course, that was after I bought a new switch, so now I have a spare. This time, I'd like to try the repair first. Anyone have experience repairing this switch?

Jeremy

Hey Jeremy,

I can't offer any assistance, but I'll simply say...I'll be watching this like a hawk. :)

Problems being hvac not coming on? I believe you can get a URO replacement fairly cheap...

The Euro replacement is only $17.06.
This is a DIY Forum................. so there are two ways to go, new part or fix old part.

Take it in to a shop, then it is a DITU. (Do it to you) :D. BEND OVER.


Charlie

Winmutt, the things that I have found so far to not work when this thing happens (with no encouragement from me) are: power windows, power sunroof, radio, add-on gauges powered from the former lighter socket. And when the problem goes away (by itself), the SRS light comes on momentarily as if it thinks the car has just been started. All of these things are powered from circuit 15R through fuses 1, 2, 12, and A. I think that includes the climate control blower but I haven't actually observed it failing yet. All fuses are newer copper fuses.

This thing has happened about four times so far, always when I'm driving along minding my own business. I first noticed the SRS light, then had a couple of occurrences of the sunroof not wanting to pop up or down one minute but the next minute it was OK. It was only the last time (Friday) when I pulled into the driveway and noticed that the window wouldn't roll down to get the mail. At that point I tried various things and took notes. Today I'll go out and see what happens. If I can get the problem to occur, I need to try wiggling the key in the lock.

As an engineer, I have a psychological need to fix the thing myself, especially after putting $100 into an unnecessary new switch for the '96. OTOH, a new OEM (Mercedes) switch is less than $40 from Fastlane.

I still would like to hear from someone who has R&R'd the switch. It's supposed to be removable through the cluster opening without disturbing any of the lock parts. I can't find a mention of it in the FSM and most of the forum threads discuss the 123 and 126.

Jeremy

Jeremy, Your lock assembly looks almost like a carbon copy of the 123. the only way to remove the ignition switch on the rear of it, is to remove the whole thing. 3 screws hold the ignition switch on the rear.

I have done 2 123`s, and not all that difficult to do. maybe a 124 is :confused:.

http://12.153.160.115/images/catalog...1244622030.jpg

Charlie

The problem isn't with the lock, it's with the physical electrical switch attached to the end of the lock assembly. Maybe.

I had a lock assembly that wouldn't fully return to position 2 (run). So I had to jiggle and center the key in the run position for everything to work properly after starting it. When you have the assembly out, make sure that its operation is smooth. The best repair if it is bad is replacement. There's no repairing a worn lock assembly.

But the answer to your question depends on how long you can be without your vehicle, and how many times you want to take the assembly out of the vehicle. If you destroy the switch or fail to effect improved operation of the switch, then you have to be prepared to be without your vehicle for a few days and / or to R&R the switch twice to fix it once. If those two possibilities are okay for you, then go for the repair.

I completely get the need to repair rather than replace. I just tried to repair a sealed relay from an espresso machine that wasn't making contact. It turned out that the contacts were destroyed, so I had to get a new one, but I removed/attempted repair/replaced the bad relay onto a circuit board while waiting for the new one. Didn't work, but still had to try. Caffeine withdrawal will make you do strange things...

I'm going in "There" twice?
 

(Not for the same thing?) for a less than 20 dollar NEW part?

Y'all let me know (Please) how you got this apart and back together [+ Fixed]without destroying it?

(Somewhere there's a Picture of the innards that GSXR posted,AND it shows
the Plastic detents inside the electrical portion wear away and prevent proper
operation of the Switch)

Whilst in "There":

Please see reply #11:
http://www.peachparts.com/shopforum/showthread.php?t=82226&highlight=diamond

Charlie doesn't give a source for his $17.06 part (and probably not allowed under forum rules anyway) but I prefer to use a "gen-you-wine" MB part for this application.

As for the post #11 in the link, it seems to apply more to removing the lock assembly when the key doesn't work. In my case, the lock cylinder is newish; I replaced it myself, a trivial job, my old lock worked well but I wanted one key for everything on the car. (The two-key problem was inherited with the car, one of the many boogers I had to pick.)

I hope to be able to remove the electrical portion without disturbing the rest of it but maybe not - in a thread I found, gsxr said it was a PIA. If the plastic innards are worn such that the contacts don't 'make' properly, I'll replace the switch. It depends on how the switch is made.

Can't find gsxr's pictures - must have not searched with the right keywords.

Thanks for the advice, people.

Jeremy

It's all about the 1Lb "Locking Bolt"
 

Jeremy,

The reference to reply#11 AND REMOVING the Bolt assembly is/was because
ALL the accelerated Stress/Wear on the Electrical Portion of the IGN Sw system
is due to the necessity of Throwing that bolt back and forth.

I'll be willing to bet Key/Leaves wear decreases dramatically,also with the Bolt
Gone.

[I gotta admit my anti-theft deterrent is a remote RF Battery disconnect,that
no thief will ever locate.So loss of the Bolt's Security function is moot to me.]

Jeremy, look your part in All Part Express for your yr/model. click on electrical then ignition switch.
Genuine---- $35.69

URO---------$17.05



OK, I was off by one ¢. :rolleyes:

Charlie

My post (#11) was not in regard to the tumblers/key cylinder. It was in regards to the rest of the locking assembly. In my case, it appears that the return spring couldn't overcome the worn parts, so it would bind a bit after starting. I replaced the key cylinder and lubed the lock as best I could, but it didn't help. I could move the switch with the key to the Run position after starting, which was a minor annoyance but an easy fix as far as I was concerned. A year or two later I ended up replacing the entire lock assembly when it started to jam up trying to move it out of the 'lock' position. The key cylinder is not the culprit in this situation. It is the lock assembly. Thus my advice to ensure your lock assembly is in good order, and that it returns the key cylinder solidly on its own to the run position after starting

And as far as the return spring, that too is part of the lock assembly. I have a new switch assembly in my parts bin, and it has detented positions, but no spring that returns the assembly to the run position.

Granted, this all applies to a 123, but charmalu's post indicates the assemblies are very similar. The main difference seems to be the different mechanical connection for the switch. So that's the basis for my post. YMMV.

Ok - as you all may have read, I've been having starter problems. Just coinsedence (or not), my ac quit working yesterday (clutch not engaging). When I shut the car down it wouldn't start.

Also watching this one to see if that switch is rebuildable for a friend - and maybe me in the future.

Allpartsexpress is unhappy tonight
 

There is some problem tonight with the Allpartsexpress site . . . all it lists for the '87 300D is Accessories & Hardware, Brake Components & Wheels, and
Chemicals. I'll try again tomorrow.

LOL