It has done this 3 times now since January (good thing I live in a dry climate) – 1st time it cleared after 3 or 4 days on it’s own. Did it a second time and cleared within a day. 3rd time (now) it’s been 2 days, spent several hours ripping stuff apart and back together, but it’s still there.
I should note, the car was parked each and every time it did this.
Thought, OK, got a moisture issue either in the REM or the CEM. Pulled the REM, it’s dry, looks ok visually. Put it all back together. Checked the connector under the windshield cowl drivers side, it was all dry, but resealed it with silicone anyway.
Pulled the CEM out just to make sure there wasn’t some other water path – it was also completely dry on drivers side. I DO (or hopefully DID) have a small water leak on the passenger side from the fan inlet – and recently replaced the fan motor and control block on it, and dried it all out and cleaned it. when I had the cowl off.
I started checking connectors, found a slight dampness on the drivers side under the seat with the connector (assume it’s the drivers rear drain for the sunroof, yay – will address it soon enough) so dried out the connector 54/40 (sends the signal from CEM to REM) and used silicone on it as well. With it unplugged, no lights, instant I plugged it back in (key out) the lights came back on.
I also tried a different relay on RMI5 in case it was stuck – it’s good.
Also, since I was grasping at straws, I pulled the BCM – it was dry, checked it over visually, and reinstalled it.
I’m stuck at how to pull info off the CAN and see if it will tell where the signal is creeping in at. Is it just a 21 year old CEM deciding to flake out, but why then only when wet outside and not from driving through a puddle? REM is same, but when you cut the CAN to it, it turns the lights out.
I’m going to plug VIDA Dice into it again – last time it did it, I plugged in, and the only codes I had were the (missing) AUM, the Climate Control Air Quality sensor out (anyone know where to get a new one?) and an O2 sensor (bad heating element) that I have the part for, but haven’t tackled yet.
I’m open to suggestions – any ideas? The electrical controls engineer in me wants to run wire from the CHMSL to the brake lights down low and being done with it… but I’d rather it work correctly if it’s something fixable.