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Trailer Lighting Problem

krazykarl

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krazykarl Enthusiast

krazykarl

Posted
Posted

I have a 03 Silverado 1500 with a trailer lighting problem I'm hoping someone might know what I could try. The old 7-way trailer adaptor was corroded so I replaced it and tested the lights. I then found corrosion in the factory adaptor near the spare tire. I eliminated this adaptor and hardwired everything. I went to test the lights, everything works accept:

 

The drivers side brake light doesn't come on.

When the brakes are applied and I turn the passenger blinker on the driver side blink also for about 15 seconds, then it comes on constant like it should since the brakes are applied. If I then turn the passenger side blinker off both brake lights continue to work. If I stop applying the brakes or turn on the drivers side blinker and then turn it off the drivers side brake light stops working.

 

Everything else is working properly. I've tried finding a better ground with the same results.

 

Thanks for the help!

nbscanuck Enthusiast

nbscanuck

Posted
Posted

Sounds like wiring issues on the trailer. Might have to do some checking for broken and exposed wires on the trailer.

DofD Senior Enthusiast

DofD

Posted
Posted

I'd take a meter and test all the pins on the plug on the truck. If they all work okay, then there is something up with the trailer wiring as Darcy mentioned.

Draenor Senior Enthusiast

Draenor

Posted
Posted

IIRC the wiring should be:

 

white- ground

yellow- left/brake

green -right/brake

brown -tail

light green - backup

blue -trailer brakes

red - 12 volt +

light blue -Stop Lights * DO NOT USE*

 

 

This is for an '04. I know that GM changed it up from the '03 to '04 models. I had a light blue wire, for stoplights. I did not use it, but the stop lights work fine getting juice from the yellow and green wires.

krazykarl Enthusiast

krazykarl

Posted
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Posted

I've been testing everything with a test light, I haven't even tried hooking it up to a trailer yet, so I know it is a problem with the truck. I also tried grounding when testing directly on the negative terminal of the battery with the same results. Are there other grounds in the circuit that I could check, if so, where are they located? Also, are there any relays or other things in the circuit that could go bad?

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