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Hi all, I hope that someone can give me some advice. All the turn signals/indicators on my car are stuck solidly/permanently on, even with the ignition switched off.

The turn signals no longer work. For example, if I move the indicator stalk to signal left or right, there are no clicking or blinking sounds. All signals outside the car, and the green indicators on the pinnacle remain permanently on. It's the same when I press the hazard switch. All the lights remain stuck on.

I'm having to leave the car with the battery disconnected in order to turn out the lights.

I've read various posts that suggest that the problem might lie with the combination relay (N10), such as this one.

hxxps://forums.mercedesclub.org.uk/index.php?threads/n10-relay-soldering-repair-wiper-indicators-hazards-rear-window-demister.62702/
(https changed to hxxps, can't post links as a new member)

I was hoping to be able to buy/re-solder the relay to fix the problem.

To investigate this problem, I pulled out the relay. The thing that surprised me was that even after I removed the relay, all the turn signals still remained permanently on. I imagined that pulling the relay would cut the power, and therefore turn off the lights. Because of this, I'm starting to doubt whether or not the relay is the cause of the problem. Could someone comment on this?

At the moment, my plan is to buy a replacement relay from Ebay to see if a replacement solves the problem.

But before I do this, are there any other probable causes of this behavior, or are there any other things that I can investigate?

Many thanks :)
 

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2002 Mercedes ML320, Mercedes 190E 2.3L (sold), 2001 Mercedes c320(gone)
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Hi all, I hope that someone can give me some advice. All the turn signals/indicators on my car are stuck solidly/permanently on, even with the ignition switched off.

The turn signals no longer work. For example, if I move the indicator stalk to signal left or right, there are no clicking or blinking sounds. All signals outside the car, and the green indicators on the pinnacle remain permanently on. It's the same when I press the hazard switch. All the lights remain stuck on.

I'm having to leave the car with the battery disconnected in order to turn out the lights.

I've read various posts that suggest that the problem might lie with the combination relay (N10), such as this one.

hxxps://forums.mercedesclub.org.uk/index.php?threads/n10-relay-soldering-repair-wiper-indicators-hazards-rear-window-demister.62702/
(https changed to hxxps, can't post links as a new member)

I was hoping to be able to buy/re-solder the relay to fix the problem.

To investigate this problem, I pulled out the relay. The thing that surprised me was that even after I removed the relay, all the turn signals still remained permanently on. I imagined that pulling the relay would cut the power, and therefore turn off the lights. Because of this, I'm starting to doubt whether or not the relay is the cause of the problem. Could someone comment on this?

At the moment, my plan is to buy a replacement relay from Ebay to see if a replacement solves the problem.

But before I do this, are there any other probable causes of this behavior, or are there any other things that I can investigate?

Many thanks :)
Hi, sorry for the issue you have, could this be a short circuit somewhere? Seems most probable. I'm almost 'obssessed' with having diagnostic scans whenever possible, as much as possible. If you can get access to star, they could take a scan and get pointers to possible electrical shorts. An old wire or two may have become brittle and the insulation flaky, causing electrical bridging.

I think some wires with lights had degradable cables on the cars of that era, start by unplugging the lights and plugging back one by one, see if something changes.. don't know if that helps.

Sent from my PH-1 using Tapatalk
 

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Discussion Starter #3
Thanks for your help. I think you might be right in that there might be a short circuit somewhere. I'll see if there's anyway in which I can try and trace it. I'll take your advice about unplugging the lights to see if that makes a difference.
I'll report back later....
 

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1995 C280 (165K mi)
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this is going to be a hard diagnosis. what is the model, year, miles, condition and service history?
 

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Thanks for replying MB-W202. It's a 1996 C180, 145k miles. It's in pretty good condition for its age, and is serviced at an independent MB garage.
 

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1995 C220
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For what its worth, I had a similar problem about 12 years ago, and if memory serves, I originally thought it was the turn signal stalk, because the wiper would not come on either. The difference though, was my lights would stay on solid and not blink when the turn signal was put on. When car was shut off, they shut off. But changing the relay did fix it. It does seem strange that they are on all the time. It makes me wonder if you have a short on the ground side of the circuit. Time to get a schematic and a test light and start doing some probing. The relay may be ground switched or positive switched, this is important to know when testing for the problem.

On a side note: one thing I never realized about test lights until recently, is that you can check power AND ground with it. I have always used one by clipping the one clip onto the negative post of the battery(or anything that will provide a good ground) and probe for 12 volts on a circuit. But you can also attach the clip to the positive post instead, and use it to check for a good ground, which is painfully obvious to me now that it was pointed out to me, but a good tip none the less. This may help in your diagnosis; if a wire is grounded and lighting the test light when it is not supposed to, that may be a sign of your issue. One other tip; if you do get a test light, get one with a regular bulb and not an led bulb. The led bulb may light up in the test light, but the regular bulbed ones when lit up prove that the circuit can handle the amps(led bulbs dont use much amps.) You could have a wire that is broke but hanging on by one strand, that will light up the led test light but not the regular bulbed one.

Good luck
 

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1999 C280 (sport), also 2001 SLK230
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Hey MrW202,

This is a bit of a guess, but perhaps these thoughts would help. First, it strikes me that if you removed a relay and absolutely nothing changed, then the odds are that the relay isn't the problem. Also, relay faults tend to be visually observable, e.g., burns on the circuit board, poor solder joints (use a magnifying glass and look VERY closely at where the solder meets the circuit board), or sometimes the little wires on the coil of the relay will be visibly broken. If you find none of this, I'd look elsewhere.

And my first bet is that the device that creates the blink is what your problem is. That device is some kind of electro mechanical device that intermittently supplies power to the various lights that blink. It seems likely to me that something inside that thing may be fused and providing solid power all the time.

Unfortunately, that's a guess based on logic. I don't know where that thing sits or what Mercedes might call it. But I think it's a fair bet that that's where your problem resides.

Best of luck,

Kim G
Boston, MA
Where electronics are likely no happier than in the British Isles.
 

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Discussion Starter #8
Hi georgebuhr - many thanks for your great advice about how I go about testing and probing the circuit. I've learned a lot from your post.
CheckEngine - thanks also for your comment. It collaborates my suspicion that the relay isn't the cause of the problem.

I joined this forum just the other week and I'm touched by how so many have given their time to help me. It's a wonderful community and I'm very grateful.

Unfortunatly, I don't understand too much about car electronics, so I'm undergoing a bit of steep learning cycle at the moment. This means I won't be able to progress this quickly, but I will report back with my findings.

Thanks once again everyone :)
 

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1999 C280 (sport), also 2001 SLK230
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@MrW202

I found this article which might be of help: You are being redirected...

One of the easy things it suggests is to push your emergency flasher switch in and out several times in case something inside it is stuck. Seems cheap and easy.

Another thing the article says is that simultaneous failure of both SAM modules is not uncommon.

Do your windshield wipers work correctly? I'm asking because the switch is part of the turn signal stalk. I just looked on autohausaz.com, and they have a new turn signal stalk assembly, supposedly OEM for about $70 USD. That's not bad if it turns out that's what you need. I don't know if they ship to the UK, but I've dealt with them a lot in the USA and highly recommend them.

Best of luck,

Kim G
Boston, MA
Where we are trying to figure out a nagging transmission problem.
 

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Discussion Starter #10
Hi @CheckEngine

Many thanks for sending me the article.

I really hoped that pressing the flasher switch in and out several times would help, as that would have been such an easy fix! Unfortunately, the problem still persists.

Following your advice, I tested my windshield wipers and I noticed that they weren't 100% right. After I plugged the battery back in, I pushed the end of the signal stalk. Usually, this would spray the windshield with fluid and activate the wipers for about 3 swipes. When I tested it, it sprayed the windshield, but didn't activate the wipers. I then tried all 3 speed settings for the wipers. All 3 settings worked fine. I then tried pushing the stalk again and on this second occasion, the wash/wipe feature worked! It all seems fine now, but I think there is something not quite right.

Following @noetico's advice, I disconnected all the lights and plugged them back in. Unfortunately, this didn't help either.

Unless anyone has any further suggestions, I think my options are currently.....

  • Continue testing for a short circuit
  • Try and diagnose if the indicator stalk/switch is at fault
  • Try and diagnose if the SAMs are faulty (maybe I can only do this with a STAR diagnosis)
  • Try and move the car to a garage with STAR diagnosis
 
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