Weirdest electrical issue yet

[TriX5]

Michel, welcome!

Upon re-reading your post it seems like a wiring break. Since you only get this problem in motion. This will be tough to find but some scouting might show where work has been done on the loom or maybe from installation of aftermarket electronics.

The other things that come to mind, make sure your ground connections are tight. Some of the items you mention are governed by the GM module, windows, wipers. GM modules are cheap and could be worth trying a swap.

As to help, the only good BMW indy I know about is in the north, Autohuis Buursema in Leek. If you are near there, you might try them, they seem capable.

[timmyc]

TriX has a great suggestion: Check the grounds. All of them!

I seem to remember swapping a motor years ago on an older Bronco and we didn't tighten the ground strap from the block to the firewall and I was having all sorts of weird happening. Turns out that's what it was. We had only put it on finger tight, so when we were looking around, it looked like all was well. Only after putting a wrench on it did the ground actually ground. Coincidentally, I just had another ground issue that was making my lights wonky. Grounding is very important in the electrical loop!

Welcome and good luck!

[workingonit]

Originally Posted by timmyc

TriX has a great suggestion: Check the grounds. All of them!

I seem to remember swapping a motor years ago on an older Bronco and we didn't tighten the ground strap from the block to the firewall and I was having all sorts of weird happening. Turns out that's what it was. We had only put it on finger tight, so when we were looking around, it looked like all was well. Only after putting a wrench on it did the ground actually ground. Coincidentally, I just had another ground issue that was making my lights wonky. Grounding is very important in the electrical loop!

Welcome and good luck!

I had a similar issue with my '73 Volvo 142 back in 1976. It would drive fine, then sputter, and the lights would flicker, and suddenly be OK again. After a dozen incidences, I put it in the local Volvo shop for that problem, and one other (Bosch fuel injection surging at idle), and they couldn't find any electrical problem, even after miles of test drives.

Within twenty minutes of leaving the shop, the sputtering/flickering occurred again, so I drove to my Grandfather's house to park it (and borrow his car). I went directly to Radio Shack and bought my first good multimeter, and long test leads & clips. Then, I proceeded to test every ground in the car. I found nothing wrong, so I asked my Grandad what he thought.

He said that he'd disconnect/reconnect all electrical grounds one at a time. He reached over and grabbed the main battery ground in preparation to disconnect, and moved it about two inches, when my meter showed no continuity. I then removed the cable (good condition on both ends, with a light blue plastic sheathing...I can see it in my mind), and stripped the sheathing off of it; there was a corroded section at the mid-point of the cable, with zero corrosion showing elsewhere.

If I, or the Volvo techs had simply flexed the cable far enough, the problem would've been spotted. Afterwards, I figured that the sputtering/flickering incidences had all occurred on roads bumpier than the smooth city streets that the techs test-drove on.

[bcredliner]

Originally Posted by TriX5

Michel, welcome!

Upon re-reading your post it seems like a wiring break. Since you only get this problem in motion. This will be tough to find but some scouting might show where work has been done on the loom or maybe from installation of aftermarket electronics.

The other things that come to mind, make sure your ground connections are tight. Some of the items you mention are governed by the GM module, windows, wipers. GM modules are cheap and could be worth trying a swap.

As to help, the only good BMW indy I know about is in the north, Autohuis Buursema in Leek. If you are near there, you might try them, they seem capable.

Welcome!