2005 XC90 Burned CEM and DTC Troubleshooting

[onekruss]

This is my first post and I could really use your help. First time Volvo owner with some significant electrical issues.

I have a 2005 XC90. Recently, two blocks from my driveway, my wife hit the windshield washer to clean off pollen. Immediately she smelled an "electrical smell" and lights went wacky on dash. She shut it off. After at tow and a failed diagnostic at local shop who said they could help, we took to dealership.

Dealer first thought alternator, then CEM, which it turned out to be after a confirmation bench test and replacement by xemodex. The team at Xemodex was helpful and provided guidance to find what may have caused the burn fault on the CEM. The Volvo dealership was HUGELY uncooperative in continuing to diagnose/troubleshoot the suspected areas pointed out by xemodex.

So, I am beginning to dig in myself. I have the Control Module - Diagnostic Trouble Code with suspected items of concern as follows:
CEM-8F2C Windshield wipers. Signal too high. DTC is found not active
CEM-DD21 LIN-bus 2. Signal missing. DTC is found active
CEM-DD30 Communication with ACM module. Signal missing. DTC is found Active
CEM-1A52 Communication with DDM control module. Signal missing. DTC is found not active.
CEM-1A53 Communication with PDM control module. Signal missing. DTC is found not active.
CEM-9C03 Antenna/light ring. Signal missing. DTC is found not active.
CEM-DD10 Communication with LSM controm module. Signal missing. DTC is found not active.
PSM-0028 Operating button, memory 1. Too long time. DTC is found not active.
UEM-0004 Siren Communication fault. DTC is found active.
UEM-0005 Sun room Communication Fault. DTC is found active.

Can anyone help me decipher this information?

Also, xemodex initially indicated:
Our technicians stated that the location of the burn on the PCB was located between two pins: C32 Volcan Lite and the D11 Rain Sensor.
They would like you to use a multimeter to check the resistance values for the rain sensor and pin C32. Please check for a short to ground or power.

But further phone discussion with their team suggested troubleshooting for failure in:
CEM 4/56-> Wiper Motor 6/1 BL-W at pin C:31, and
CEM 4/56-> RSM 7/149 W at pin D:11

I'm hoping someone can help me find a causal factor before I plug in the CEM replacement. Don't want to burn that up! If you may lend a hand, please PM me and we can chat offline.

Thanks in advance for your help!

[oragex]

the CEM goes sometimes bad because of water leaking on top of it, from the sunroof drain tube that passes under the dash. the burnt smell seems to indicate a shortcut either on a electronic module or on wiring. I would start inspecting visually the wires under the dash and near the ECM under the hood.