Ignition switch problem w140 - PeachParts Mercedes-Benz Forum

1994C220 · #1 01-09-2003, 09:40 AM

First of all, I wanted to thank everyone for their help with the three Mercedes I have had the pleasure to own the past couple of years. I have an M class, an S class, and recently just sold my beloved C class car.

This morning, when I went out to start my car, I couldn’t get the engine to turn over. The battery seemed fine, and all the warning lights came on, but the car did not even make an attempt to start. I tried several times, right as I was about to give up and take the other car, it jumped to life. This is not the first time it has done this, but the times in the past when it wouldn’t click over, I would just take out the key and put it back in, and the car started on the second try...This morning, it took several trys...I guess its getting worse, and I want to make sure I fix it before Im left stranded. I did a search on ignition switches, but mine doesn’t seem to be experiencing the same symptoms. My key is not hard to turn, nor does it stick. It just doesn’t seem to “catch on” ignition wise...Please, any help would be appreciated.

savagetom · #2 01-09-2003, 11:13 AM

It could be the starter solenoid sticking. You can diagnose the next time it does it by tapping on the starter while the key is turned. If if starts then it is probably the starter.

Good luck.

1994C220 · #3 01-09-2003, 11:30 AM

Thanks for the help...a couple of questions...where exactly is this part on my S320...and, is it easy(cheap) to just replace the part? It its 30-50 dollars, and its easy to get to and replace, maybe I should just go ahead and replace it anyway.Thanks for your help

ILUVMILS · #4 01-09-2003, 08:30 PM

A W140 ignition switch would be quite a challenging job for a DIYer! It's not really hard to do, but it's not really hard to mess up either. Don't confuse ignition switch replacement with tumbler replacement. Remember, the ignition switch is the first line of defense against theft! It's made to be a bit confusing intentionally. I've seen more than one not-so-experienced person have all kinds of trouble with this job. Proceed with caution.

savagetom · #5 01-09-2003, 09:55 PM

I'd be surprised if it is the key switch. That doesn't seem to be a very common failure mode. They sometimes stick but ususally the switch is still good. I took a look at the EPC and it looks like the solenoid can be ordered separate although I don't see it in PartsShop. On the other hand the start assembly is only $216 at PartsShop versus $700 on the EPC.

One way to determine if it is the switch or the starter is to jump 12V dirctly to the solenoid with the key off. If it starts then but not with the key then it must be the key switch or the wiring.

I don't know for sure where the starter is on this car. I've never messed with mine. But gernally speaking they are usually on the passenger side of the motor down low. Access it from underneath.

Good luck.

Gilly · #6 01-09-2003, 10:14 PM

I have replaced several ignition switches in 140's and also 129's, which use the same style switch. This is EXACTLY what happens, they lose circuit 50 (starter position). I am almost positive the car needs an ignition switch.

Gilly

myarmar · #7 01-09-2003, 11:40 PM

Also check transmission shifter switch. Try to start in N position instead of P. The other posibility would be K38 starter lock-out relay.

1994C220 · #8 01-10-2003, 09:14 AM

Thanks for the replies...I will check all of these this weekend. The car started fine this morning(thank goodnesss...i overslept), so its more of an inconvenience at the moment. But I know that if you let things on a mercedes go unchecked, you could have twice the problems in the future.

Thanks again, Ill keep you posted.

Peter Guenther · #9 01-10-2003, 09:40 AM

I have a similar problem on my 92sel, it comes and goes, I have trided repatedly tuning the ignition on and of to see if the contacts clean. I did feel less tension on the key when it does not start see if you can confirm, that will rule out the starter, or the solenoid

1994C220 · #10 01-10-2003, 10:00 AM

I think it might be the switch...I will pay attention to the key next time to see how much friction I feel. I am also going to try the "starter tap" as well. I will post any observances here...and if you find out anything new, please do the same. Is there any type of spray or oil that would help clean contacts? If its as simple as some cleaner, it would free my time up to devote to the other problems that need my attention(compressor, seatbelt, headrests).

Gilly · #11 01-10-2003, 08:26 PM

No, if it's the switch I recommend replacing it.
Next time it acts up, just try holding the key in the start position for maybe 10 or 20 seconds.

Gilly

1994C220 · #12 01-11-2003, 11:28 AM

Ok...if Gilly says its the ignition switch, thats what it is...Thanks, Gilly. Is this a DIY project? or are there too many things that can lead you to disaster? Id like to attempt it myself, if you think its possible.

Thanks.

Gilly · #13 01-12-2003, 09:21 PM

It's kind of a pain to do it. It could, I suppose, lead you to needing it towed to a shop to have the job completed, I don't know if you call that a disaster. To me, a disaster is the car catches fire, or you screw it up and causes you to have an accident. That's not likely to happen.
One hard part is getting the panel removed under the drivers side of a dash, there are 2 catches hidden under the instrument panel, hard for me to tell you how to release the catches.
Then removing the switch is kind of a puzzle, like most MB ignition switch/lock work. At least the lock stays in the steering jacket, it makes it a little easier. If your not familiar with removing the under dash panel, and/or never done any MB ignition switch or steering lock work, I'd tend to steer you away from doing it.

Gilly