auto dim mirrors.

[ALc5exclusive]

hi all.. my 2009 c5 x7 has the auto dim mirrors but only the drivers side mirror dims now. is there a fix/mod/bodge for them, or is it a case of replacing them with new ones..

cheers

Al.

[jamescarruthers]

I know on my C6, which has presumably the same sort of technology, that the self-dimmiing wing mirrors are about £350 per piece of glass! I’m hoping the C5 X7 is less for your sake. I replaced one… it’s really good and dark when required and makes the other original look like it’s not working! In time they seem to loose their dimming effect.

[ALc5exclusive]

ha anyone actually repaired one?

[GiveMeABreak]

It's deciding on whether it is the mirror (that contains the electrodes and liquid solution) that is faulty or the electrical connection to the mirror. I've never heard of the glass unit going faulty to date.

Before checking the guidance below, and as this is the driver's door only that is faulty, I'm inclined to think it may be a wire that has worn at the door, where the protective sleeve shields the wiring from where they go through from the bulkhead to the door. The opening and closing over the years weakens the wires and they can break - and as the Driver door is the one opened the most, this is where the damage mostly happens. So I'd remove the grommet / sleeve, and look carefully at the sleeves of the wires for a break, before dismantling the door card to check for the direct connections to the mirror.

Secondly, I would check the plug and or the electrical connections to the mirror. See below for the connector channels: You may have a 10 way black connector too - ignore that, which is for the folding / repeater and mirror motor controls.

Driver’s exterior rear view mirror connections
Allocation of channels of connector (Black 6-way )

Channel number	Designation
1	Left-hand rear view mirror position potentiometer + control
2	Left-hand rear view mirror position information (HIGH/Low)
3	Control - Left-hand rear view mirror position potentiometer
4	Left-hand rear view mirror position information (Left hand /Right)
5	Exterior electrochromatic rear view mirror supply output
6	Exterior electrochromatic rear view mirror earth output

Passenger’s exterior rear view mirror connections
Allocation of channels of connector (Black 6-way )

Channel number	Designation
1	Right-hand rear view mirror position potentiometer + control
2	Right-hand rear view mirror motor information (HIGH/Low)
3	Control - Right-hand rear view mirror position potentiometer
4	Right-hand rear view mirror motor information (Left hand /Right)
5	Exterior electrochromatic rear view mirror supply output
6	Exterior electrochromatic rear view mirror earth output

[Paul-R]

Marc, it's the driver's side that does work. The passenger side is the one that doesn't dim.

It could still be a broken wire though.

[GiveMeABreak]

Oh, thanks Paul - I misread that, so same applies, worth a check on the passenger side first as it's the easiest and cheapest check.

Basically, the 2 wires that I have marked in Red in the table are marked as follows on the wire sheath:

Passenger Side 6 Channel Wiring Block:
Pin 5: 6445F (Exterior Electrochromatic mirror supply output)
Pin 6: 6446F (Exterior Electrochromatic rear view mirror earth output)

So these numbers should help you identify at the door aperture grommet which ones are for the electrochrome function.

Both these and the Driver's side counterpart wires go to the internal Rear View Mirror, and from there to the supply and the BSI, as the mirror dimming function is activated from data received from the internal rear view mirror front and rear brightness sensors.

[jamescarruthers]

By the way, did the passenger mirror ever dim? Mine nom-dimming mirror had been broken in a previous ownership and was replaced with a non-dimming version for fairly obvious financial reasons!

[ALc5exclusive]

By the way, did the passenger mirror ever dim? Mine nom-dimming mirror had been broken in a previous ownership and was replaced with a non-dimming version for fairly obvious financial reasons!

yes the passenger mirror did dim briefly and the drivers door still does.... it looks like il have to get the multi meter out and im guessing that when the rear view mirror stops dimming, it needs replacing?

hmm.. just found a rear view auto dim on ebay for 16 quid.. might be worth a punt

[ALc5exclusive]

yup... replaced the rear view and it works now.. just got the nearside to sort next