Ground issue??

[MolsonCanadian]

Hey folks, here is my issue, I'm running out of ideas.

1972 C10, 350/350, fresh paint on everything, recently reassembled.
Using stock harnesses.

HEI wired to 12v, no issues with engine. Extra wires for old coil setup coiled and ziptied in corner.

All lights wired properly, as far as I can tell.

Headlight grounds to core support cleaned and tight.

Added ground straps to the following areas:

Large strap - block to frame
cab to frame
bed to frame
core support to frame

Marker lights and tail lights work fine
signals only work when hazard switch is in ON position.
Brake lights cause all front marker (bumper and side) to light up when depressed.
Installed new signal light switch assembly, same issues.
Cleaned mounting/grounding areas on rear light pots

Am I missing a ground somewhere?

[lutronjim]

Sounds like switch but you replaced it. Are bulbs full brightness? If so I would try to see if you have some wires shorting in the column.

[MolsonCanadian]

Originally Posted by lutronjim

Sounds like switch but you replaced it. Are bulbs full brightness? If so I would try to see if you have some wires shorting in the column.

Thanks, yes, they seem to be full brightness. The switch isn't actually installed, its sitting on the seat, plugged into the harness. The only items left to replace are the headlights, as the ones I have came with the truck and are questionable.

[ray_mcavoy]

Originally Posted by MolsonCanadian

signals only work when hazard switch is in ON position.

That might be due to a bad turn signal flasher. Try temporarily swapping the flashers for the turn signal and hazards to see if the problem moves to the hazard lights or stays with the turn signals.

Originally Posted by MolsonCanadian

Brake lights cause all front marker (bumper and side) to light up when depressed.

Check all of your bulbs to make sure they are the correct ones. I've seen a few cases where someone accidentally put an 1156 single contact bulb in a double contact socket meant for an 1157 bulb. That creates a short circuit between the brake/turn and parking/marker lights, causing all of them to light up together. The little pins on the sides of the bulb base are offset on the 1157 bulbs (vs. straight across on the 1156's) in order to prevent them from fitting in the wrong socket, but some sockets are loose enough to allow them to fit when they shouldn't.

Originally Posted by MolsonCanadian

Installed new signal light switch assembly, same issues.

It's unlikely that you'd have the same issues with two different switches. But if you've ruled out everything else, you can try unplugging the turn signal switch and simulating it's function using some jumper wires.

Originally Posted by MolsonCanadian

Am I missing a ground somewhere?

It sounds like you've added enough ground straps to ensure that all of the major body components are well grounded. Although, there could still be issues with the light fixtures themselves making good ground contact with the body. Especially with fresh paint on everything. A simple way to check for a bad/missing ground is to run a temporary ground wire directly from the negative battery terminal to the bulb in question. That can usually be done with the bulb still in it's socket by removing the lens and touching the end of the temporary ground wire to the bulb's metal base.

[Greasey Harley]

Did you use star washers on all the grounds?

I just cured all kinds of electrical gremlins on my K10, by cleaning and replacing all the grounds and replacing all the external ground washers.
I just bring it up because there is no mention of it.
If all the grounds are proper, you should have very low resistance from one component to the other.
Did you check resistance across all your grounds?
I don't know, just brain stormin'. Let us know when you figure it out.
Good luck,
-Russ

[Andy4639]

Originally Posted by MolsonCanadian

Hey folks, here is my issue, I'm running out of ideas.

1972 C10, 350/350, fresh paint on everything, recently reassembled.
Using stock harnesses.

HEI wired to 12v, no issues with engine. Extra wires for old coil setup coiled and ziptied in corner.

All lights wired properly, as far as I can tell.

Headlight grounds to core support cleaned and tight.

Added ground straps to the following areas:

Large strap - block to frame
cab to frame
bed to frame
core support to frame

Marker lights and tail lights work fine
signals only work when hazard switch is in ON position.
Brake lights cause all front marker (bumper and side) to light up when depressed.
Installed new signal light switch assembly, same issues.
Cleaned mounting/grounding areas on rear light pots

Am I missing a ground somewhere?

It sounds like you have some wires crossed up some where. The brake light switch shouldn't effect the front of the truck at all unless the wires are crossed up.
Have you looked at the wiring diagram for it on here to see what you have?

[Wgesnerjr]

"Brake lights cause all front marker (bumper and side) to light up when depressed."

I had a 76 a Trans Am in high school. I bought it from a guy who was convinced it had a wiring issue. Front turn signals would come on when brake pedal was depressed. My bother in law (who worked on cars for years when he owned a gas station) knew exactly what it was. Turns out someone crammed an 1156 bulb in one of the brake light sockets. It was jumping the two contracts in the plug and making all kinds of weird stuff happen.

The guy sold it super cheap because of a wrong bulb. That 1156 worked out GREAT for me!

[kaycee]

Like they mentioned check all bulbs and grounds ,I add a ground from eng. to frame or alt. to frame.What does your fuse panel look like clean or rust cruddy looking?

[bigmoe]

You said your truck was just painted. Did they happen disassemble the front clip and paint all the components separately? The paint layers can cause a poor grounding between the various parts. You ground the headlight to the bucket but ground still has to go through the bucket to backing plate, backing plate to rad support, rad support to frame, etc. What I did was attach the headlight ground wire directly to the rad support behind the headlight and I ran ground straps from the frame to the rad support (one on each side) so the ground doesn't have to go through as many attachment points. Clean down to bare paint and use good quality star washers.
Also at the back of the truck run a ground strap from the frame to the box.

[jeff_wilson70]

I solved a bunch of gremlins by running a dedicated ground from the neg batt terminal then split to each bucket to the headlight ground. The headlights are super bright and solved the gremlins when I turned the headlights on

[dennislbrooks]

Did you put in a new steering column or column wiring harness with turn signal switch? I put a brand new A body tilt in my 442 and the signal switch in the steering column was wired incorrectly. 2 wires were switched. The only fix for mine was to literally fix the error in the switch. Re-soddering was a pain.

[MySons68C20]

I'll go with Mcavoy on this one....I had a similar issue and replacing the flasher did the trick.
This happened shortly after I installed a new American Autowire complete harness with their flasher. Sometimes stuff fails right away even if you just installed it.