W211 door mirror wiring

[donkmeister]

I have a 2004 W211. The mirror adjustment on the passenger side was not working, I suspected the usual issue of cracking wires on the hinge, and when I stripped it down that was the case.

Someone had already been in there and bodged it horrifically in the past so rather than repair, I decided to buy an "OEM-quality" mirror unit from Eurocarparts and start afresh.

On my original, there are TWO wires that connect to the mirror glass via little spade connectors, for the mirror heating. On the replacement, there are FOUR wires, ending in a small four-pin connector.

Am I correct in thinking this four-pin connector is for auto-dim feature plus heating? I.e. this is an LHD driver-side rather than an RHD passenger-side.

Can I use an adaptor or snip the wires and omit the dimming connections without upsetting the car? If so, which wires carry the power for heating?

Everything else appears to be correct with the new unit.

 

[Druk]

Don't snip anything. Just tape up what you think may be redundant. Then if it's not you can experiment.

 

[donkmeister]

Don't snip anything. Just tape up what you think may be redundant. Then if it's not you can experiment.

Thanks Druk. I hate to snip wires if possible, there's always a chance I might want to have symmetrical auto-dim mirrors in future! But, that would require buying a new glass for the mirror too.

The thing I'm not sure about is which of the 4 pins are the conductors required for heated mirrors. Is there a wiring diagram or other that shows this? Or do I just have a completely unsuitable mirror unit and need to return it?

The fallback is to whip the old one off and check what pins on the two 6-way connectors go to the heated mirror connectors, but I bet someone can forewarn/forearm me with the what-pin-connects-to-what information before I get the torx out again.

 

[Diesel Benz]

See wire colours from the attached diagram. Wires for the heating element are also thicker.

 

[donkmeister]

Thank you, I'm afraid that wiring diagram doesn't correlate with what is on my car - perhaps it changed for the facelift?

I have two 10-pin connectors at the door end of the mirror loom: a white one with 8 wires in it and a black one with 7 wires. 3-pin connector (2 wires) at the powerfold motor, 8-pin connector (7 wires) at the mirror adjustment motor, 4-pin (4 wires) for the indicator and 2 wires (with spades) for the heater element.

I took the old mirror off again and compared the wiring with the new one - the new mirror motor only has 3 wires instead of 7. Sensors in the old one, perhaps?

Any thoughts? Are there any redundant wires? I know ECP won't take something back if they suspect it has been fitted so don't want to try it on the offchance all features still work.

 

[donkmeister]

UPDATE: I've read elsewhere that the additional wires are position feedback for the memory function.

Makes sense really, the car needs to know where the mirror is so it can adjust it.

Annoying, seeing as I deliberately checked the new one was for memory function before ordering it. RMA raised with ECP. Hopefully they can source the correct part!

 

[Diesel Benz]

Sorry about the wrong diagram. I thought you would have a RHD car (the default at this site) even if you did say it is a RHD model.

 

[donkmeister]

Thanks for the help and the wiring diagrams.

In the end I eventually ordered the correct part from ECP. I never managed to find a part number label on the old one, I had to figure it out from the Russian part numbers website!

Price-wise: the Mercedes indy wanted about £350 for a genuine OEM part, the Mercedes franchise about £300, but from ECP it was about £150 for a non-genuine but full fit/form/function part. I would have rather got an OEM part, but that's £150 saved toward my next service instead.