The Stovebolt Site Forums The Shop Area The Electrical Bay '71 Rear Electrical Issues

Truck in question is a '71 Cheyenne. The problems are thus:

1) Headlights on - nothing works on the back. No markers, tail lights, nothing.
2) Brakes - Everything out back will light up dimly. Tail lights, markers, all of it. This happens with lights on or off.
3) Blinkers - Either direction will cause everything to flash dimly. Tail lights, markers, all of it. This happens with lights on or off.
4) The left tail light bulb gets burned up quickly. It takes very little usage before it's no good.

In troubleshooting I tested at the connector where the tail light harness plugs into the main harness. Everything tested properly on the main harness. I went to start looking at the tail light harness and it was such a rats nest that I just yanked all of the wiring and replaced most of it. The pigtails for the tail lights looked okay so I reused them. When I was done everything worked properly, which was just last night. All turn signals, marker lights, tail lights, and brake lights worked fine. After driving the truck around town today it's now back to the same crap. Does this sound like grounding issues? It sure seems like it to me. The lights did all work fine just a month ago, so it is perplexing and I am not sure what else to look at at this point.

Sounds like a ground problem to me. Connect a ground wire from the bed to the chassisYou could run grounds from the mount studs on the rear lights to the frame. Make sure the ground is good from the socket to the housing.

Agreed. Your bed grounded with the mounting bolts from the factory. They aint grounding so good now.

It was the grounds, you guys nailed it. I ran two ground straps, one on each side, from the bedsides to the frame and that solved everything. Before I put the straps on I did verify the issue by running a small wire on one side only to the frame. Try the lights and such and no go, hook the wire up and it all worked. I can also say that those lights on the back are far brighter than they have ever been. Amazing what proper grounds will do! Thanks for the help!

My '71 C10 was grounded to the passenger's side head. That is good, as far as it goes, but I felt that additional grounding was needed, so I dropped a #4 cable from the block to a bolt hole in the frame. Then I added an 8 gauge ground to the right inner fender. I made sure that connection points were clean and shiny and used star washers as well. I didn't use but one ground in the rear to the bed. Be sure to add a heavy 6 or 8 gauge ground from the frame to the cab as well.

On my truck, every previous owner must have thought he was God's gift to wiring because I have a couple boxes worth of Scotch locks and butt splice crimp ons that I removed.

I rewired everything from the harness plug on the drivers side in back and that and the new grounds made all the difference in the world! Solder and heatshrink are your friends!

I also switched to a 10SI alternator with internal regulator at the same time I did the other rewiring. If you haven't done this, it is well worth your time and important if you are also switching to HEI as I am.

Best wishes, Les