Mirror Demister Circuit?

[sinewave]

Got a fault listed on my nearside mirror on the demister circuit.

Upon striping down I find I have a permanent 12V on the heater wires where as on the the Drivers (offside) power is only energised when instructed to via STAR.

I assume that both mirrors demister circuits are controlled via the front screen demister screen button? Didn't test this as it started to rain.

If so are there separate relays for each mirror and thus could the nearside relay be stuck on?

 

[whitenemesis]

What year is your car? On later cars the door mirrors are heated constantly at temps below 15c. Not controlled via the screen demist button

 

[sinewave]

Tiz a 57 plate.

I had heard that from a mate who works at BMW which is why I tested the offside also which is not throwing up a fault.

This side only energises when you click the operate button on STAR where as the nearside is on permanently and is throwing a code on quick test.

 

[andy27168]

Not sure if they have changed it but from about 97-98ish the heated mirrors were supplied via the door control modules, which in turn were switched from the CAN BUS to put the mirror heaters on. But this would imply you have a faulty DCM which I would of thought would of been indicated by STAR.
What was the ambient air temp when you did this test?

 

[sinewave]

Yesterday, so about 21 degrees C

I think it does state a fault on the DCM.


Where is the DCM located for the nearside door gear?

 

[whitenemesis]

Inside the door.

 

[sinewave]

Will see if I dare have a crack at removing the door card!

I still remember shreading a Rover SD1 door card years ago by not knowing how they came off without trashing them!

 

[whitenemesis]

Search ebay, many vids on door card removal.

 

[sinewave]

Ah!

Never thought of that!

Cheers! (I assume you meant YouTube not eBay?)