Hi Saabtechtalk.
New to the forum and I apologize for any misspelling since english is not my first language.
I hope that someone have any suggestion to what is going on with my car. I know that I am "just" missing the door mirror heat/demist function, but I would like to have everything working on my car ;-)
I noticed a few month back that I did not get any heat in the RH wing mirror. Old mirror measured defective and changed to new - still no heat. Now I am facing no heat in either door mirrors. Both mirrors are brand new aftermarket quality mirrors with 14-15 ohms resistance when measured.
Until now I have been able to feel some heat in the LH door mirror very periodically. Works for a short period of time and does not come back on if I deactivate the rear screen heat and reactivates it again - which I have been told should activate the mirrors again for a new cycle?
When starting the car then I can measure 14,3V at the mirror wires with a multimeter. These 14,3V can be measured both with deactivated and activated rear screen heat, so without pressing any button. 12V test light will sometimes come on when rear window heater is pressed but will only work once.
My mechanic can measure a weak pulsing current at the side mirrors, but he cannot explain why they do not heat. Mirrors are fine.
I cannot find any DTC's when reading the fault codes with my eSID.
Side mirror motor works fine.
The rear screen heat seems to be working fine.
Everything on/in the car including all doors and windows works fine.
Fuses 5, 8 and 15 in the dash fusebox are checked ok.
As far as I can see in WIS then the mirror heat is controlled by the right rear door control module (RRDM), but the rear window heat is also controlled from RRDM. Can there be an electrical fault in the RRDM without throwing a fault code and without affecting the rear window heating??
Could it be the ACC panel switch that I press to activate rear window heat as well as side mirrors that is causing the issue??
My mechanic is talking about a defective CAN-Bus or a defective electrical wire where it splits off from the wire to the rear screen? He is talking about having the car for a full day to do a proper diagnostic search.
Any suggestions or thoughts would be greatly appreciated!
Thank you in advance ;-)