Large parasitic draw on 12v system after windows left open in rain storm

[Dovetail]

One more update for tonight. I left the new BCM mounted in place, but swapped all the plugs back into the old one so I could close the windows. Miraculously, everything seems to work now! The car starts and drives, and when I turn it off, the current drops to a couple hundred mA within minutes, then in about 10 minutes drops down to about 50 mA (probably at the lower end of what my clamp on meter can detect).

I guess I will just see how it goes for a few days before closing everythign up again. I did take the cover off of the original module when I had it out, and the circuit board looks perfect. There is no sign of any water damage.

The behavior of LeafSpy should let me know when all the ECUs are sleeping properly. Right now, when I turn the car off it disconnects from my phone like it used to, but when they were not sleeping, LeafSpy would connect just fine even with the car off.

 

[goldbrick]

Maybe it just needed a hard reset...

 

[Dovetail]

I think we have a resolution!

The original BCM was still working after a day of driving aorund, so I decided to button everything up. Once I got the switches plugged back in on the panel under the steering wheel, the symptoms came right back. Process of elimination narrowed it down to the charge timer cancel switch. I opened it up, and sure enough there is a little corrosion on the board. It is also very close to the window, so I think I can place the blame on myself for leaving the windows open after all!

Here is a picture of the board- https://drive.google.com/file/d/1Arav5PyvWiZndavyeXAvOfl5mesN-ux5/view?usp=sharing

Thank you for all the help everyone.

 

[goldbrick]

Nice job on getting this fixed, and thanks for the final update!

 

[Bickaar]

It sounds like you’ve had the exact same experience. I’ve had only you’ve been able to solve yours. Did you just replace that switch or leave it disconnected? I have been battling a dying 12 V battery for a long time. I buy my batteries from Costco and end up replacing them every six months frequently putting them on a 12 V maintenance charger but it’s hard to keep up.

 

[Stanton]

The original BCM was still working after a day of driving aorund, so I decided to button everything up. Once I got the switches plugged back in on the panel under the steering wheel, the symptoms came right back. Process of elimination narrowed it down to the charge timer cancel switch. I opened it up, and sure enough there is a little corrosion on the board. It is also very close to the window, so I think I can place the blame on myself for leaving the windows open after all!

Absolutely amazing story...and happy you were able to resolve the problem!
I wish there was a lesson in there for others (other than "don't leave the windows down"), but maybe it's persistence pays off.

 

[LeftieBiker]

I think it's "Logic buttons suck ass. Mechanical make/break buttons rule."