electrical troubleshooting with lights

[plowtruck]

Im baffled on where to go next on figuring out why my brake lights are stuck on (the third brake light sticks on too) when I turn the lights off, my brake lights turn off, they work when I apply the brake pedal but with the headlights off and daytime running lights on, my front parking lights turn on and off when I press the brake pedal. I replaced the brake pedal switch and the distribution board on the rear lights and checked over my trailer wiring harness. I inspected the wire plug ends on the dist. board and they are not corroded or broken off. I used dielectric grease on assembly of the new dist board. Still having the same problem. Can anyone steer me in the right direction? Ive searched with google and found everything I needed to get me where I am right now. I also checked the fuses under hood and in the dash and didnt find any blown. Thanks.

[gmtech4]

?the internet may not help you with your problem ,you need a schematic and mechanical/electrical experience or take it in bud

[Diesail]

I would start by testing the bulbs and sockets. Remove all the bulbs and then replace them one by one until the problem occurs. You may have a bad bulb or short in a socket.

[redxemt]

I would start by testing the bulbs and sockets. Remove all the bulbs and then replace them one by one until the problem occurs. You may have a bad bulb or short in a socket.

 

 

Agree with this. Lots of shorts occur in the sockets themselves. Also if you have a plow check the light wiring on there and disconnect the harness to isolate if you can. If you can't isolate the problem in the sockets or plow, you can isolate the wires one by one at the BCM (disconnect each one by one until the problem goes away). If the problem is still occurring, you might have a bad BCM...

 

Most wiring diagrams can be found at http://www.gmupfitter.com/index.html if you don't have them already.

 

Goodluck!

[plowtruck]

Thanks for the replies, I found out my trailer brake controller was bad. I unplugged it and lights work fine. Thanks again for the help guys