Tail lights not working

[nicholasmansfield]

I just replaced all the harnesses on my 69 c10. My rear turn signals and brake lights work but my tail lights “running light” don’t. All new bulbs and flashers as well. Any thoughts?

[72again4x4]

I’ll put this out there before everyone else does….. grounds! I checked all mine like three times and still missed one. If all your grounds are solid then maybe a pinched or loose wire.

[VetteVet]

Pull the harness plug on the firewall by the accelerator mount and apply 12 volts to the dark brown wire. If the lights don't light the problem is in the rear of the truck. I fthey do light the problem is at the headlight switch.

A bad ground is usually the issue when the lights won't light in the rear. And a blown fuse is usually the problem in the cab.

[kwmech]

Do the dash lights work?

[67C10Step]

Originally Posted by VetteVet

Pull the harness plug on the firewall by the accelerator mount and apply 12 volts to the dark brown wire. If the lights don't light the problem is in the rear of the truck. I fthey do light the problem is at the headlight switch.

A bad ground is usually the issue when the lights won't light in the rear. And a blown fuse is usually the problem in the cab.

This was my exact approach when sorting out on my 67. Once I knew from firewall to rear was working I could focus on the in cab part.