Rear view auto dimming mirror problem

[michaln7]

Hi, I have audi a3 8V from 2017 (facelift). I have retrofitted rear view auto dimming mirror but it works only about 1 day after connect connector to mirror. After about one day it stop works and I have to disconnect connector and connect it back and it starts works for another day. I have already buy new mirror, but it behave same.
What could be wrong? It is connected 1st, 2nd, 3th and 6th pin

 

[Rcord]

That's very strange. I suppose you know how to check if the mirror is working properly, that it doesn't work if the roof light is on or if there is light coming from the exterior illuminating the sensor at the side of the mirror case that points towards front, right?
So it makes me think there may be something wrong with the power source you connected the mirror. Did you connect the +VCC pin of the mirror to a switched power (it only has voltage when ignition is on) or to a permanent power fuse in the fuse box? I'm asking this because the mirror is supposed to be connected to switched voltage, so it's not powered and doesn't have any of its lights on when ignition is off. If you connected the mirror's +VCC to a permanent power source, maybe there is some issue related to the circuitry being powered for too long time. The mirror circuitry has a power MOSFET transistor at the output that drives the mirror glasses (internal and external if present) and I've noticed that the transistor gets very hot.

 

[Ice Kay]

Get a VCDS scan on your car to see if there are any faults that get picked up

 

[pburv]

Read this write up.. Might give you an idea in how it's wired up properly.
I retrofitted mine using the same part numbers listed in the first post.
https://www.audizine.com/forum/showthread.php/770337-Audi-A3-S3-auto-dimming-mirror-retrofit

 

[michaln7]

First of all, I didn't retrofited by myself, but I paid for it. I'm too worry about to I could break something.
I measured voltage between pins and:
1-2 - 12VDC
3-2 - 12VDC when revers gear, other situation 0VDC
6-2 - ~6-7VDC - little strange - I suppose that should be 0VDC or 12VDC (+VCC)

I managed to check connector in roof module, and none wire of wireness from mirror go to that module. All wire go to left pillar.
I don't know what is connected to pin 6, but I think 6-7VDC is start of detection range and when is close to 6VDC mirror is working, but when is close 7VDC mirror is not dimming.
I have tried to disconnect pin 6 from connector to tests, but I don't know how and I don't want to damage it.
I have sent my tests and investigation results to company, that made retrofit in my car and I'm waiting for answer.

 

[Rcord]

Standard model auto-dimming mirror pinouts are:
pin 1 - +VCC (should be connected to switched power: 12V only when ignition is on)
pin 2 - GND
pin 3 - to reverse light (disables dimming when car is in reverse: pin receives 12V)
pin 6 - to roof module pin 3 or pin 4 depending on model (disables dimming when roof light is on and roof module sets this pin to ground).
pins 4 and 5 - output for exterior mirrors (varying 0 to about 1.5V, only connected when exterior dimming mirrors are installed)

If the auto-dimming mirror is the model with High Beam Assist, pinouts are different and the mirror is controlled by the CAN Bus. That's why it's very unlikely that you can detect some kind of fault with VCDS or other diagnosis tools if the mirror is the standard model, since it's not connected to any CAN or LIN Bus line.

Please keep us uptaded on what the retrofit company says.

 

[1Rockape]

Have you fitted mirror
81A
Or 8s0? The 8s0 has a power button on the botto. Very small with a green power on led.

Sent from my SM-G973F using Tapatalk

 

[michaln7]

81a857511 9b9

 

[1Rockape]

I think you should return to the retrofit company you paid . If not id start with disconnecting pin 6 and testing .to de pin you need to buy a depinning tool from ebay .theyre cheap enough.

Sent from my SM-G973F using Tapatalk

 

[NHN]

Yeap as above go back to the fitter, that's the best bet.

 

[michaln7]

It took some time (due COVID-19), but yesterday installation has been corrected and mirror works now.
Thank for help.