Wiring question

[Mltx2]

I'm trying to put on traditional tail lights. They light up iwth the lights on, but when the brake pedal is pressed down, the lights go out. Any suggestions? The old lights still work fine and it's a 12v system
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[lazypineapple]

Ck the grounds
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[_Ogre]

if your front marker lights go out too then you have the wires crossed

[mr48chev]

Originally Posted by lazypineapple

Ck the grounds
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Yep your lights are grounding through the other side of the bulb as it stands.

You either don't have the bulbs in the sockets right or you just don't have the sockets grounded to the truck.

[mr48chev]

Thinking on that, are you using stock tail lights as in the original GM ones or ?
How do you have them wired, stop and Tail only or for Stop/turn and tail ?

When you mounted the lights did you use any insulators like rubber or plastic between the housing and the bed ? Paint alone would be a good enough insulator to keep the lights from grounding properly. If you don't have a ground wire from the socket I'd run a ground wire from the outside of the socket to the frame of the truck.

[vintageozarks]

I agree you are missing a ground might be the body ground its mounted in rubber

[Mltx2]

the tail lights I purchased from the classic chevy dealer had just 2 wires (white & black) and a 12v two filament bulb. When I purchased the truck it had some generic aftermarket taillights that ran three wires, one wire ran the reverse light, the other two wires went to the 12v two filament bulb. I still have one of the after market lights attached. I cut the wire to the reverse light and the aftermarket light it still works correctly with the running lights & brake light. The after market light i removed was working correctly.

I'm not sure of the wiring scheme. I'm the 4th owner, the previous two owners have put in a V8 engine, front end clip and had it repainted (which is when I presume it was re-wired.
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[Mltx2]

the tail lights I purchased from the classic chevy dealer had just 2 wires (white & black) and a 12v two filament bulb. When I purchased the truck it had some generic aftermarket taillights that ran three wires, one wire ran the reverse light, the other two wires went to the 12v two filament bulb. I still have one of the after market lights attached. I cut the wire to the reverse light and the aftermarket light it still works correctly with the running lights & brake light. The after market light i removed was working correctly.

I'm not sure of the wiring scheme. I'm the 4th owner, the previous two owners have put in a V8 engine, front end clip and had it repainted (which is when I presume it was re-wired.
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[Mltx2]

I figured it out. It was a grounding problem. The two wires are hot (one for brakes, the other for running lights). The light housing itself has two threaded studs that when bolted to the mount (attached to the truck body) serve as the ground. It was a grounding problem, I was just looking at the wrong solution.

Thanks for the help and advice.
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