Reverse lights not working - '15 Cayenne

[silvernite]

Reverse lights not working when gear selector is in reverse, key on, or engine running.  I have pulled one of the lights to confirm LED is operational by jumping with 12v source.  measured voltage at plug is <1v with no change when moving gear selector from P to R.  I have unplugged and reseated the multi-function transmission switch in hopes it may just be corrosion.  But I am not sure if that switch even controls the reverse lights as it is for the Tiptronic shifting?  I do not have a wiring diagram to fully pin out this circuit, and searches for reverse switch are vague and typically refer to manual transmissions.  I don't readily see a different switch that looks like it may be the reverse switch, so i'm at a loss without some more information to troubleshoot with. I purchased this vehicle used with 127k and it was displaying "defective left tail light" , "defective right tail light" in the information cluster.  All park, brake, and signal lights work fine. I have durametric, and a FSM (no wiring diagrams though).  Any ideas or information to continue this troubleshooting would be greatly appreciated.

[silvernite]

SOLVED:

the issue was the rear BCM had been water damaged from the leaking panoramic sunroof in the past.  Previous owner apparently fixed the leaking sunroof but did not replace the BCM that had shorted out.  I purchased a new BCM from porsche and installed.  I then only had one of the two reverse lights working.  FYI you may need to recode the BCM to tell it you have "2x reverse lights" to get the other to work as well.  I only had the LH reverse light working until I found this option in the Launch X431 programming tool.

 

I now have triggered the alarm issue that causes the hazards to flash constantly with the new BCM.  I am working through this issue now.  I did notice that the Launch X431 doesn't successfully code the alarm settings, or if It does, there must need to be some other setting activated before the code will write successfully.

[JFP in PA]

You need access to a PIWIS system to code the car correctly.