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Old 12-28-2006, 02:36 PM
Join Date: Nov 2005
Location: North Georgia
Posts: 86
New to me 190E 2.3 / Strange electrical issues. Need Help.

This is a cross-post. Just want to get as much educated exposure as possible.

I just purchased my third W201. This one is a '91 2.3. It performs perfectly except for a few very strange electrical gremlins. This is one area of an automobile in which I am completely without competence.

When the ignition is completely switched off, the left side parking lights continue to burn. Playing with the switch causes some other strange things to happen such as firing the right front parking light but the lefts never go out. This is all still in the off position, btw. I'm thinking the switch is bad. I looked under there and saw the wires connected to the monster switch then travel somewhere together wrapped in cloth tape. Is there a simple plug hidden that would make it a simple replacement or do I have to take the individual wires off the old switch and put them "correctly" on a new one.

When cruising down the boulevard, sometimes the wind screen wiper likes to say hello. It will spontaneously go through its motion once or twice. I usually just wave back in amazement.

The third, and most comprehensive, issue is the pulsating lights. When the car is running, all lights constantly pulse from bright to dim. This includes the headlights. I'm thinking voltage regulator or the entire alternator but I don't have a clue where to start. It does keep the battery properly charged.

Could it be that all issues are related? I would love to replace a bad relay or voltage regulator or switch but I'm not so hot on tracing every wire looking for shorts and such. I'll do it if necessary but it will undoubtably require proper medication......lots of good, dark stout.

How about a bad ground. Could this be the culprit?

Obviously, I could use a lot of help. If you have any sparkling ideas or even random thoughts, put them out there. I like this little 2.3 and would like to get it in shape.



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Old 12-29-2006, 08:41 AM
Join Date: Mar 1999
Location: Tucker, Ga USA
Posts: 12,153
Sounds like at least 2 problems.

Yes, have the charging system checked. Also on that car & all 1991-93 190E 2.3's, make sure that the intake manifold heater isn't staying on all of the time. They had a problem with a relay sticking.

The light staying on is most likely related to the headlight switch..however make sure that a piece of old broken fuse isn't stuck between the fuses in the fuse box.
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Old 12-29-2006, 09:01 AM
Join Date: Nov 2005
Location: North Georgia
Posts: 86
Thanks, Doc

I will go ahead and replace the headlight switch. Is there a plug behind the kick panel or do I have to transfer each of the wires from the old to the new? That's certainly doable but not much fun, I can imagine. There is not much free space or wire length to work with in there.

This intake manifold heater; how would I find it/check it? I'm familiar with the 2.6 engine having owned and maintained a handful of them but the 2.3 is new to my 2.6 trained mind.

Will check and clean out the fuse box tonight.

Thanks again.


Last edited by samdon; 12-29-2006 at 09:02 AM. Reason: Left out a bit.
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Old 01-02-2007, 04:25 PM
Join Date: Nov 2005
Location: North Georgia
Posts: 86

A few things for future searchers:

The pulsing lights was traced to a faulty voltage regulator. There was spotty contact between the regulator pickups and alternator brushes. $35 (NAPA) for the regulator and all is well in that department. Apparently, Benz sells the bushings as a singular item so you could probably do this without replacing the entire regulator for just a few bills.

As for the headlight switch......Caig Deox-it did the trick. I keep this stuff around for potentiometers that constantly go south on the old tube audio gear I play with. ( has it for about five dollars. Spray it in, work the switch through its motion a couple times, then let it dry for a good hour. Disconnect the battery before you spray liquid into switch.

I'm not sure about the friendly wiper. Since repairing the other stuff it works as it should.

I'll report back with any further developments.


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