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Rewiring my sideview mirrors

4K views 10 replies 6 participants last post by  act1292 
#1 ·
This past weekend when I left my car sit out in the rain, my drivers sideview mirror gained a mind of it's own. It wants to continually adjust itself. I even pulled fuse 30 and that did not stop it. It is disconnected for now but to make a long story short, I need to replace the wires in it as they are all bare and a few are busted. I read the sticky thread on repairing but that just was putting shrink wrap tubing over the bare wires. I think my wires are past that sort of repair.

Does anyone here know the size and strand count of the wire that's used? It looks like there may be two different gauges of wires used in the mirror. Any help is greatly appreciated.
 
#2 ·
Just keep in mind how MB markets their cars..."The best or nothing"!?! The wiring on W140s is a f___ing joke. Have you replaced the engine harness yet? If not, you will. If MB really believes in the best they would recall every W140 and replace ALL the wire! Yes, I'm bitter because my S500 is about worthless due to wiring related issues.
 
#3 ·
That was a helpful post... :rolleyes:

Yes, you can rewire the mirror and it's not difficult to do. It's best and fairly simple to do if you remove the mirror from the door. That just involves popping the interior trim piece off and removing three screws inside the door.

From that point after removing the mirror cover its a matter of just cutting out and replacing each wire one at a time. Tedious, but not difficult.

The wire itself is pretty small, like maybe 18 gauge or thereabouts. I used solder and heat shrink on mine and it's still working well a year later. Be sure not to go shorter when you replace the wires or you won't be able to fold the mirror back.

Dan
 
#4 ·
Dan,
You nailed it. Another expert on this is "nhz......". I know him as Harut. He rewired my drivers mirror on my '97 CL500. I have been around electrical/control equipment all of my life and was amazed at how small the wires were (and how many there were). And I can see why if you fold them in a lot, they will not last. I have no reason to fold them in as I try to wash my own car and not send it though the car wash. As experienced as Harut was it took him more than an hour to replace all of the wiring. And please do not replace just the bad ones or you will do this all over again. Yes, as Dan said, 18 ga or smaller. And I would track down stranded wire, not solid.
Good luck.
Anziani
 
#6 ·
Eighteen gauge seems pretty large for this application. Also, the strand count is important for the flexibility in folding. I used the shrink wrap method last year on my passenger side mirror but wasn't really satisfied with the results. The shrink wrap adds to stiffness and it doesn't unfold as it should. It's for these reasons combined with the fact that several of the drivers side wires are irreparable that I want to build my own replacement harness. I have found a site that carries a wide variety of automotive wiring but I need the specs before I can order.

p.s - My engine wiring harness is original and it is just fine
 
#7 ·
Sideview mirror solution

I did a bit of research on the type of wire used in the mirror harness. It does indeed seem to be 18 gauge wire with a very high strand count. Seems to be 65/36 for the strand count with a thin insulation. I did an internet search trying to find a replacement for this. The only thing I came up with was some test lead wire but it had a thicker insulation layer.

So, I took to the junkyard for my replacement wire. At the JY I was able to find a couple of E-class models of the same vintage. They basically have the same sideview mirrors as the S-class minus the motorized folding capability. I took the harness from one of these and spliced it in. I did note that the E-class harness did not have the high strand count but I spliced it in after the bend where the mirror folds. It seems to all work well and the folding seems proper.
 
#8 ·
I generally praise the engineers at Mercedes but I think they goofed on this feature. If anything they should have offered a replacement harness with connectors at both ends so us peasants could just plug and unplug with a minimum of cost. I wonder if they put the wiring though any kind of a repetitive flex test before signing off on the mirrors?
Anziani
 
#9 ·
I had to redo both of my side mirrors because they were busted up from hail before I got the car. I found it easier to just source some from a junkyard and mix+match bits from mine and those. The wiring was all in very good shape on all four (mine and junkyard). All in all, about two or three hours of work, but that includes replacing the various trim plastic to get the best aesthetic look. I'd imagine that would be a far easier option than replacing each wire.
 
#10 ·
As a side note, it didn't seem possible to remove the internals (including wiring) completely without seriously destroying the mirror housing.
 
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