Electrial gremlin

[TexasJeff]

Okay guys I have one for all you electrical guru's out there. Over the weekend while driving my truck, all lights working normally. I pull up to a gas station to fill up, turn off the truck, shut the lights off. I fill the truck up, get back in start the truck, and pull the lights on, and no dash lights, or running lights, and the dome light is on but very very dim. You think it is a headlight switch problem or ground problem some where?

[83GMCK2500]

I have that too if I sharply pull the lights on, like snap the switch out fast. All I have to do is tap the knob back in a touch and they kick on.

[TexasJeff]

Originally Posted by 83GMCK2500

I have that too if I sharply pull the lights on, like snap the switch out fast. All I have to do is tap the knob back in a touch and they kick on.

Thanks for the info, that leads me to believe that it is a switch problem and not a ground.

[TexasJeff]

Well it was not the headlight switch, replaced it and still doing the same thing. Anyone got any idea's about the grounding circuit for the running lights on these trucks.

[old Rusty C10]

are you sure its a short and the alternator didn't take a dive on you? If its truly just the lights id check the ground on the negative cable and the ones on the firewall by the lights

[mrolds88]

Last alternator I had take a dive on me didn't act like this. Truck would start and run fine (it was a F*^d F600.) But if you turned anything on the truck would shut off. Was kind of funny when I hit the turn signal going down the road. Also if it was the alternator, I don't think that you would have part of the systems not work. With the dome light dim, I think I might look at that wiring first.

[TexasJeff]

The truck runs perfect, alternator is charging fine I just have no dash lights or running lights. I am pretty sure it is a ground problem, I though it might be the cab lights, but checked the ground on each of those and no problems. I will cheap checking all the grounds on the running lights.

[Boom]

The easiest way to determine if it's the ground at any light is to supply a new ground using a jumper and see if it turns on. What's the voltage at the headlight switch power supply with switch off and on. Does it vary by very much? If it does drop then I would suspect a bad connection

[john]

How about a blown fuse?

[hatzie]

You're looking at three different grounds...
The front running lights and headlamps ground on the radiator support.
The tail lamps ground behind the left taillight to the bed.
The dome-light / courtesy-light circuit is always hot with switched grounds... to the doorway through the plunger switches and the dash ground stack through the headlamp switch.

The one common part is the switch.
The dome lighting dimly when it's not supposed to points to a bad switch.
Check the fuses as well but my money would be on the headlight switch.

[Gryndar]

Just a suggestion. Check the dimmer switch, if it's bad it can cause a voltage drop that can mimic and bad ground.

[f.monroe]

Running lights and dash are the same circuit. My old truck would occasionally blow the light fuse and I found a shorted wire under the bed between the bed and frame. The dome light may be some freaky side effect of the lights seeking ground .
Frank

[Greenlee]

Ground problems can cause strange symptoms like this. When I replaced the wood on my bed I started having all kinds of problems with the lights. I was pulling my hair out checking all the wiring, and then I put a simple ground strap from the frame to the bed and that fixed all of my problems.

[cool68]

have same type of problem - fuse for dash lights will blow out but, dome and all other lights fine. put in one of those glow fuses in so, that you can see in the dark exactly what fuse goes - the faint glow provide some interior light. replace fuse and turn lights on everything is fine, next time the fuse blows. any ideas?

[augwld]

As I stated in another post and say often,small engine mechanic by trade,90% of all electrical issues incur a bad ground. My opinion is insert a new ground and see what happens. Cheap and easy test/fix. Also clean all connections. Corrosion or dirt will affect electrical systems, and it costs only time to sand and reconnect wiring.

[motornut]

seen the dim dome or random light go on ,when the drivers door pin gets dirty
some drivers have two wires ,one for the lights on/key/door open buzzer too
not sure the effect shorting those

[monte0185]

Check your tail lights and turn signals bulbs. Most likely you have one that has a shorted socket that's back feeding the light circuit. Easiest way to determine which one front or rear is to start in the rear by unplugging the rear connection under the bed altogether. Then move to the front and pull bulbs one by one till you find the shorted socket. Shorted sockets can do all kinds of weird things to happen.

[TexasJeff]

Thanks for all the input guys, It was way to cold out (for this wimp anyway) this weekend to work on the truck. I will try all the suggestions and get back to you when I find the problem.

[monte0185]

Originally Posted by TexasJeff

Thanks for all the input guys, It was way to cold out (for this wimp anyway) this weekend to work on the truck. I will try all the suggestions and get back to you when I find the problem.

Dont blame you there. Really wanted to work on the CC dually this weekend but it wont fit in the garage all the way. LOL