W204 indicator.

[Chrisalex]

My passengers side wing mirror indicator has stopped working and brings the error message on the dash frequently.

At first I thought it would be a straight swap for the wing mirror shell with the LED unit built in, I have since realised that the LED only works once the cars locked and the wing mirrors are folded and once folded out they no longer work. That being the case it’s more likely got to be a wiring issue.
Has anyone any advice on how to carry out a repair myself rather then going to the dealers. Is it easy enough to access the harness.

Any help will be greatly appreciated.

 

[EmilysDad]

On my car (R Class) the inner door card needs removing to access where the mirror/indicator wiring plugs in to its control box. I'd expect yours to be similar.

 

[Chrisalex]

Providing the door card can be removed easily it should just be a case of doing continuity tests on the wires if the harness does indeed plug into a control box there.

 

[umblecumbuz]

On the 204's, when you remove the door card, there is revealed an aluminium panel covering the entire inside of the door behind the door card. This is riveted to the steel door frame all round, and the window mechanism and door locking gear is behind this panel.

I had to remove one to access and replace an inoperative door lock, and it was a pain. I can't remember whether the mirror wiring and plug is behind this aluminium panel or not. I don't think it is, but if it is you have a fairly long job on your hands.

 

[Chrishazle]

If you need to get the mirror glass out to get to the wiring behind, it's a bit of a pig. I replaced both indicator units on my S204 a year or so back, got genuine MB ones from MB Newcastle via eBay, watched a good Youtube video about changing them, tried to remove the glass from one side, gave up for fear of breaking something so took it to my indie who swopped both for £20CIH in about 15 mins without damaging anything. IIRC the replacement indicator units were not that expensive, maybe £15-20 each.

 

[Chrisalex]

If you need to get the mirror glass out to get to the wiring behind, it's a bit of a pig. I replaced both indicator units on my S204 a year or so back, got genuine MB ones from MB Newcastle via eBay, watched a good Youtube video about changing them, tried to remove the glass from one side, gave up for fear of breaking something so took it to my indie who swopped both for £20CIH in about 15 mins without damaging anything. IIRC the replacement indicator units were not that expensive, maybe £15-20 each.

I’m pretty sure it’s a wiring issue as the LED’s work when locking/unlocking the car. When the mirrors are out they don’t work.
I have been quoted £140 for the LED unit as it’s bonded the the wing mirror shell.

 

[Chrisalex]

On the 204's, when you remove the door card, there is revealed an aluminium panel covering the entire inside of the door behind the door card. This is riveted to the steel door frame all round, and the window mechanism and door locking gear is behind this panel.

I had to remove one to access and replace an inoperative door lock, and it was a pain. I can't remember whether the mirror wiring and plug is behind this aluminium panel or not. I don't think it is, but if it is you have a fairly long job on your hands.

How easy is it to remove the door card on the w204? It may be worth my while having a quick peep to see if the box is on the outside of the aluminium panel, hopefully outside.

Did you just drill the rivets and pop some back in?

 

[Chrishazle]

Hang on, what breed of C220 do you have? Thread title is 204, your latest post says 205 - and IIRC wing mirror indicators are different pre and post facelift (MY2011) on 204's, mine's pre and the indicator is one strip, I believe post facelift it's 2 strips (as is, I believe, the 205). Mine is certainly not bonded to the shell.

 

[Chrisalex]

Hang on, what breed of C220 do you have? Thread title is 204, your latest post says 205 - and IIRC wing mirror indicators are different pre and post facelift (MY2011) on 204's, mine's pre and the indicator is one strip, I believe post facelift it's 2 strips (as is, I believe, the 205). Mine is certainly not bonded to the shell.

Sorry mate, I’ve just edited it.

It’s a facelift W204 with the 2 strips of LEDs which are bonded to the mirror casing.

 

[umblecumbuz]

Don't think they are bonded.
I believe they are held both by their shape in the mirror housing and also by a small adhesive strip (double-sided tape).
If so, once the mirror outer casing is removed - it is clipped in place and will come away from the mirror body by careful juggling - the led moulding can be carefully removed by using a hair dryer and a screwdriver. Soften the tape with the hairdryer and gently ease it away with the screwdriver.
You will need to remove the mirror glass to get to the wiring behind it. The led's are just plugged in.

If you need to remove the door card, there are three (4?) hidden screws - one is on the top of the door reveal - and the usual clips around the card which need to be prised apart. As you make a gap, the wiring plugs for the door card electrics will be visible and can easily be reached and disconnected.

 

[Chrisalex]

Don't think they are bonded.
I believe they are held both by their shape in the mirror housing and also by a small adhesive strip (double-sided tape).
If so, once the mirror outer casing is removed - it is clipped in place and will come away from the mirror body by careful juggling - the led moulding can be carefully removed by using a hair dryer and a screwdriver. Soften the tape with the hairdryer and gently ease it away with the screwdriver.
You will need to remove the mirror glass to get to the wiring behind it. The led's are just plugged in.

If you need to remove the door card, there are three (4?) hidden screws - one is on the top of the door reveal - and the usual clips around the card which need to be prised apart. As you make a gap, the wiring plugs for the door card electrics will be visible and can easily be reached and disconnected.

Excellent, thank you for the detailed response, that’s great.
I am pretty sure it is the loom because the indicator flashes fine when locking the car and the mirrors are up, however once unlocked and in the down position the indicator no longer works and the dash error message appears again, surly if the LED’s have packed in they wouldn’t work intermittently.

I will give this a go but it won’t be for a week or so now as I’m busy with work.

 

[umblecumbuz]

I recall that Malcolm (Television), who was a great contributor to this forum before his death, deduced that with folding mirrors the culprit for intermittent operation was nearly always the wiring loom where it entered the mirror body. So your diagnosis looks correct.

If so in your case, you may be able to track down the fault by just dismantling the mirror itself - as above - without resorting to door card removal.

Hope it works for you.