M42club.com - Home of the BMW E30/E36 318i/iS

DISCUSSION => Electrical => Topic started by: erupert66 on June 14, 2012, 09:19:53 PM

Title: Electronics on Relay protected circuits dead
Post by: erupert66 on June 14, 2012, 09:19:53 PM

I am working on a '91 318is that I bought for my son for his first car.  We completed and engine swap (no 6 cyl for him though LOL) as the PO put the #2 Rod through the block.  The car sat about a year.  Ran pretty good but the starter was hanging and would continue to run after the engine started even with the key on.  changed out the starter but now, it seems like the main stuff protected through the various relay circuits (Kx slots in the fuse box) are not working.  No power to the fuses controlled by the relays.  The relays test out ok and there seems to be power on the correct pins.  I have an e30 electrical troubleshooting guide and I talked to my brother who thinks it might be ground-related.  Anyone here have any experience troubleshooting this or any thoughts?

The car isn't tagged yet so we pick at on the weekends so I'd like some ideas to check out this weekend.  

Thanks

Title: Electronics on Relay protected circuits dead
Post by: DesktopDave on June 15, 2012, 07:28:47 AM

There is a relief relay that is designed to shut off power while the motor is cranking, that would be my first guess.  I think it's a standard relay, but if you've tested the whole set it might be a little deeper.

I've also noted an under-voltage relay.  I think it's near the steering column on e30's.  It'll shut down the whole car to protect the electronics from low voltage damage.  In that case it might just be the battery...