DIY: Retrofitting an auto-dimming rearview mirror in cars with Rain/Light sensor

[West CRO]

Sorry for bringing this thread up again. Has anyone retrofitted EXTERIOR dimming on A5? I have took off A pillar and I have seen wires passing near airbag but I haven't seen mentioned T27 connector from first post. Help please

[Smac770]

The autodim interior mirror has two status wires coming from it. They both go to both door control modules. I don't think it's a 2-wire CAN bus, would seem overkill. Maybe just redundant wiring? The door control modules then have two wires that go to the 2-pin plug on the autodim exterior mirror.

You should have the wiring diagrams document for your vehicle, along with the rest of the relevant workshop manuals for your VIN, from erwin (erwin.audi.com for Europe). But if you don't, you can find an old copy at cardiagn.com.

T8c/5 > T27a/25 > T20f/17
T8c/5 > T27c/25 > T20g/17
T8c/4 > T27a/7 > T20f/8
T8c/4 > T27c/7 > T20g/8

The exterior mirror connections are pins 2 and 6 on the 16-pin plug.