No Brake Lights or Turn Signals, but Head, Tail, and Reverse Lights Work.

[618 Syndicate]

97 GMC K1500, no brake lights or turn signals, there's no power to the trailer wiring connector when brakes, turn signals or hazards are on. Fuses are good. Front marker lights work, front turn signals are not. We've replaced the brake light switch, didn't fix it. Any thoughts?

 

[Nad_Yvalhosert]

Multi function lever assy is usually my first area to test, but... have you tested for power coming out of the brake switch? Check where the brake controller is connected. The white wire is usually suspect. The terminals seem to pull out of the pigtails on ones I've seen

 

[618 Syndicate]

Ok, thanks. We'll check.

 

[97C1500TJ]

I had a similar issue and before you go pulling your switch, check the ground behind the rear bumper on the frame. Mine was disconnected

 

[618 Syndicate]

Grounds were checked, sorry should have stated that.

 

[someotherguy]

Did you temporarily remove the trailer harness for testing? Seen them cause problems more than once, especially the nice tee-in style with the weatherpak connectors that slips right in between the frame harness and rear lamp harness.

I'd disconnect everything downstream of the harness on the frame right near the end of the driver side frame rail and test at that connector to see if juice is getting that far, then go from there.

It's pretty rare without obvious damage to not at least have power to that point; the problems are usually downstream of it.

Richard

 

[HotWheelsBurban]

Yes I'd vote for the multi function switch, or the wiring to it. That's what my Burb did a few years ago, and replacing the switch fixed the problem. Third brake light worked, but the two main ones didn't, and no turn signals either.
And the trailer connector harness can have problems too. That's why I don't have one on the Burb right now. The part between the factory harness halves was fine, all the truck lights worked. But no power to the trailer plug....will order a new one from RA next paycheck. Don't need it till October now, no swap meets before then.

 

[thegawd]

I agree with Someotherguy. I had the same problems on my Burb when I first got it. the problem seemed to be inside the adapter. after determining where the problem was, I cut all of it out, soldered and shrinkwrapped everything back up once it all worked.

 

[618 Syndicate]

Multi function switch was evidently the issue....
Thanks all.

 

[someotherguy]

It's a bummer to hear of another multifunction switch crapped out, but good to know for future reference this is becoming more common for some reason.

Richard