1989 Chevy 1500; no power to light circuits

[leroyd92]

I'm at quite a loss with a issue we have on this truck. We lost positive to everything at the back of the vehicle. I took a positive wire and stabbed into the bezel connector and all elements function. Except for black which should have been negative. The truck sat for a small amount of time and when we started working on it again today we noticed that the headlights are out also. We have not forced positive to the headlights because it's currently 110° outside.

All the info I find on the internet is hodgepodge between 87 and 93 or 94. Some sources claim the truck has a headlight relay. I don't believe this truck has one. The headlight switch does function, there's power in and power out on the other two wires to the connector once it's hooked up. I feel like something simple has occurred that were overlooking. If somebody could shine some light on what wires under the dash feed the tail lights and or the headlights that would be fantastic.

Essentially I'm trying to find some clarity as to what this is.

There is currently no power going to brake lights, tail lights, and running lights at the rear of the truck.

To me this sounds like a wire came loose or something shorted out at some point. The brake light fuse was popped when we started this whole ordeal a few weeks ago. So something had to have shorted out or unsoldered itself.

Thank you everybody in advance

 

[PontiacHO]

Check the wires at the starter and follow up from there. A wiring diagram really helps. Also check all the body grounds.

 

[eljefino]

Big wiring problems like yours are actually easier to solve than more arcane ones.

-- If you have flash-to-pass by pulling the turn signal stalk, do the high beams work?
-- Do you have dash lights?
-- Do you have the factory stereo? If not, what's in there?
-- Do you have front parking lights?

There is a body connector for the wiring harness somewhere back there under the bed-- simply unplugging these and re-plugging them can sometimes get them working if there's a bit of corrosion that gets scraped off.

And don't forget grounds, if you're probing for positive and assuming the ground is good, you may bark up the wrong tree.

 

[ka9mnx]

Darn mice are chewing my wires again.

 

[leroyd92]

Big wiring problems like yours are actually easier to solve than more arcane ones.

-- If you have flash-to-pass by pulling the turn signal stalk, do the high beams work?
-- Do you have dash lights?
-- Do you have the factory stereo? If not, what's in there?
-- Do you have front parking lights?

There is a body connector for the wiring harness somewhere back there under the bed-- simply unplugging these and re-plugging them can sometimes get them working if there's a bit of corrosion that gets scraped off.

And don't forget grounds, if you're probing for positive and assuming the ground is good, you may bark up the wrong tree.

Front running lights are the only thing working.
Factory stereo is there and never been touched, it died 20 years ago
I don't believe the dash lights work when I played with the dimmer.

I know there's something really stupid going on...

 

[clinebarger]

Might as well start at the main positive Bus Bar on the right side of the firewall, The headlight switch is fed directly from the Bus Bar, The same wire also powers portions of the fuse block.

If you find a burnt fusible link...Do Not jump unfused power to that circuit!!....Find the reason the link burned.

 

[leroyd92]

Might as well start at the main positive Bus Bar on the right side of the firewall, The headlight switch is fed directly from the Bus Bar, The same wire also powers portions of the fuse block.

If you find a burnt fusible link...Do Not jump unfused power to that circuit!!....Find the reason the link burned.

We checked them already. All are intact and working. No sign of burnt and stabbed the wire for continuity 6" down from the eyelets