E31 95 840 - no power windows, wipers or interior lights until car warms up

[95e31]

Having an issue where certain electrical will not work until car is driven for about 30 minutes.
After sitting for 4 hours or more all power is lost to windows, windshield wipers, interior lights, trunk lock, maybe other things.
Problem resolves itself after driving about 30 minutes.
If you wake in the morning and it's pouring you're calling a Uber.
I met one other 840 owner with the exact same problem and he was not able to resolve it.
One shop thought they had it down to one of two relays but couldn't be sure.
Anyone seen this?

[M6csi]

Everything points to the classic general module (gm 2) failure. A lot of good gm2 info here. There are 5 electrolytic capacitors on the circuit board that generally fail over time and need replacing, then everything should be all good. Forum member ‘eedegretodrive’ is the person to seek if you need repair for the general module.

[shogun]

could also be a fusible link with haircracks

[olinjohnston]

Having an issue where certain electrical will not work until car is driven for about 30 minutes.
After sitting for 4 hours or more all power is lost to windows, windshield wipers, interior lights, trunk lock, maybe other things.
Problem resolves itself after driving about 30 minutes.
If you wake in the morning and it's pouring you're calling a Uber.
I met one other 840 owner with the exact same problem and he was not able to resolve it.
One shop thought they had it down to one of two relays but couldn't be sure.
Anyone seen this?

Basically everyone has seen this if they have tried to operate an E31 in cold temperatures:

https://www.bimmerforums.com/forum/s...re-Electronics
https://www.bimmerforums.com/forum/s...nk-do-not-work
https://www.bimmerforums.com/forum/s...epair-reminder
https://www.bimmerforums.com/forum/s...very-5-seconds
https://www.bimmerforums.com/forum/s...zy-in-the-Cold
https://www.bimmerforums.com/forum/s...-on-cold-start
https://www.bimmerforums.com/forum/s...hing-in-my-840
https://www.bimmerforums.com/forum/s...indow-Question

[95e31]

Everything points to the classic general module (gm 2) failure. A lot of good gm2 info here. There are 5 electrolytic capacitors on the circuit board that generally fail over time and need replacing, then everything should be all good. Forum member ‘eedegretodrive’ is the person to seek if you need repair for the general module.

- I think this is it!

[M6csi]

Coincidentally, the original general module on my 91 850 failed a few days ago. It exhibited all the classic systems of a dead gm. I had planned to do the capacitor replacement for quite a few years now but have never found the time or procrastination is probably more appropriate.

After almost 30 years of operation, it was just a matter of time before the eventual gm failure. Oddly enough, a couple weeks back, I ordered all the replacement capacitors (still waiting for some to arrive) to do the gm repair. In the meanwhile, I also picked up another gm off a 95 coupe to have as a backup. Fortunately for me, the spare gm arrived the day before the gm death the next morning. Popped in the ‘new’ module and everything was back to normal. What perfect timing heh? I’ll replace the capacitors on both gms when all the parts are gathered.

[8eights]

I wouldn't bother repairing them as EE chargers 50 bucks and a super quick turn around.