Got my turns signals, brakes, reverse lights working. Spent a few hours diagnosing, but got a brain storm while having a bathroom break. Final fix after pouring over electrical diagrams was the fuses! No they were not blown! I usually ohm out the ends of the fuses (not the spades but the little slot on the ends where the lettering is), and they checked fine. Started pulling them out and found white corrosion. I had some spares other where dressed up with a wire wheel. I used electrical connector grease when re-installing. I have been using electrical grease on every thing electrical for years on other vehicles. My advise is to always use electrical connector grease. I even used it on battery terminals. I reground the negative connection at the motor, but I am curious where the rest of the Jeep gets the ground at. Usually they are grounded at the block and body. I can't find the body ground. Does anybody know where it is?

 

I also revived the engine ground. Cleaned up, installed star washer to ensure good ground. Installed electrical connector grease.

 

Gotta love it when that happens!

 

I was pulling out some relays from a donor vehicle and noticed the white oxidation you speak of. Having an electronics background I thought to myself that cannot be good.

Motivated me to pull every fuse and relay in my XJ's, clean up the contacts with some contact cleaner and inserting and removing the fuses/relays a few times. I also reinstalled them using electrical connector grease.

Gotta wonder how many Jeeps are out there with odd intermittent problems that can be traced to this?

I know in my late 1980's GMC pickup I had an intermittent problem in the dash. We tore that dash apart to look for a problem. Found nothing and put it all back together. The problem " went away ", my best assumption was tearing apart and reseating all the connectors did the trick.

 

Theres one behind the temp sensor sending unit, its a braided flat cable from the block to the firewall. I think that's the one you're talking about...