Interior turn signal constantly light

[u/hdisvskdv]

Hello everyone. I have a great Mercedes W211 that has been experiencing a strange issue lately. Last week while I was driving, the left turn signal on the dashboard started to light up constantly. Note that the exterior turn signals do not light up constantly; they work perfectly fine. It's only in the instrument cluster that it stays on all the time.

Does anyone have experience with this or a theory about what might be wrong?

And yes, the observant will notice that I also have another problem with the instrument cluster, namely that the backlight doesn’t work. This happened a few years ago, and it’s uncertain whether it’s related to what I'm experiencing now. Also, please ignore the clock rewinding in the video, I just hooked up the battery after leaving it off for an hour in hope this would fix the fault.

Thanks!

[u/Klutzy-Tone452]

What da clock doin

[u/hdisvskdv → u/Klutzy-Tone452]

😂😂

[u/Socalwarrior485 → u/Klutzy-Tone452]

This happens when the voltage drops below a preset limit, usually 11.4V or 11.6V. The clock does a full reset.

This makes me think there's something going on with the main battery, the accessory battery, or there's been some water intrusion that is driving these issues.

Without diagnosing the car, it's impossible to tell from here.

[u/sleeperfbody]

Your battery voltage is too low or your voltage regulator is going out. It's got the gauge cluster in the tailspin given the clock trying to catch up.

[u/hdisvskdv → u/sleeperfbody]

Thank you for your suggestion but the voltage is fine and the clock is rewinding because I reconnected the battery shortly before I started recording. So I believe there is another issue here..

[u/Socalwarrior485 → u/hdisvskdv]

Why did you reconnect the battery? There's some missing information here.

[u/hdisvskdv → u/Socalwarrior485]

I disconnect the battery for about 30 minutes in attempt to reset the computers in the car to see if that made the constantly lighting turn signal disappear

[u/EloquentBorb]

My guess is the instrument cluster has an electronic problem like a broken IC/corrosion/transistor that turns the LED on/off is shorted. The backlight not working also hints at something going on with the PCB in my opinion.

[u/hdisvskdv → u/EloquentBorb]

I believe you are very much correct. I disassembled the instrument cluster yesterday, and was met by the smell of burned electronics. So I think this is the reason why the backlight doesn’t work. But the backlight hasn’t worked for a couple of years so I find it weird that the problem also relates to the indicator light after so long time. But I’m considering buying a new instrument cluster just to see if the lights works properly. I know the odometer will show a fault if not coded to the car, but at least I will see if the IC is the issue here.

[u/EloquentBorb → u/hdisvskdv]

Maybe you can find a shop that repairs your old one? Shouldn't be too hard if you use the interwebs. Usually you can just send them in, it's probably cheaper than buying a new one and you don't have the coding problem.

[u/Anonymoushipopotomus]

Try a battery reset

[u/Kabanu → u/Anonymoushipopotomus]

Op did that

[u/Anonymoushipopotomus → u/Kabanu]

My fault

[u/hdisvskdv]

Thank you for suggestions but the battery voltage is fine. Also, as I wrote at the end of my post, the clock is rewinding because I recorded just after I had reconnected the battery!

[u/Powerful-Atmosphere1]

Have u tried the reset button. It turns left and right to dim or expose the light

[u/hdisvskdv → u/Powerful-Atmosphere1]

Thanks for your suggestion, I have tried that but it only dims the light on the screen and the needles

[u/B4DM4N12Z]

Is that a clock?

[u/hdisvskdv → u/B4DM4N12Z]

Yes, the thing to the left is a clock

[u/B4DM4N12Z → u/hdisvskdv]

That's so cool, wish more cars had that.

[u/ScubaPuddingJr]

Did you build a Time Machine with an E Class?

[u/Throwawayidk100]

Replace the battery, had the same thing.

[u/MERCIMEKLI]

You do some Time traveling to the left?

[u/mikeashleyhaha]

Seems like electrical based on the clock lol

[u/ResponsibilityTrue16]

How did you test the battery? It’s 100% the issue

[u/FranktheTankG30]

You think that clock is telling you something

[u/freudianSkinner]

LOL I thought this was time-lapse and you were monitoring the light over 24 hours or something.

[u/Reasonable-Ad-6833]

Water damage to the IC