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Discussion Starter · #1 ·
I have been having trouble with the lights on my trailer. I think that i have traced it back to the fuse block. I think that it is the flasher behind the fuse block that is for the trailer only. Is there a way to test the flasher before i have to spend the money to get a new one. The flasher is GM part no. 15764135.
 

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Did you connect a DVM to the 7 pin harness where the trailer connects to and see if your getting proper voltage readings there? I dont know of any other way to test the circuit. Otherwise, what strange lightig are you getting from your trailer?

-Bryan
 

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Do the trailer brake lamps work? They use the same wire/fuse. There is a seperate trailer left and right turn fuse in fuse panel at the edge of the dashboard, driver's side.

I have never seen or heard of a seperate flasher for the trailer circuit. If it was seperate, the trailer and truck signals would blink at different rates:confused: .
 

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Discussion Starter · #4 · (Edited)
when the truck is hooked up the the trailer, the right brake light is always on, just not a bright. even when the truck is not on. all the turn signals work just no break lights. when i unplug the flasher and plug it back in everything works fine untill i cycle though the turn signals and brakes.
this is the only think that i can think of being wrong. when i check the fuses, sometimes the left light would blink when the right siganls is on. (this is on the trailer only)
i am clueless. i checked with the local garage and the want $63 for the flasher. i just want to make sure that this is it
 

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I would check the grounds, I have seen it where the the wrong side or the marker lights all flash because the ground is no good and the ground though a greased ball is not as good, Going down the road they would work at times then work wrong.
 

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runnwo;1534108; said:
I would check the grounds, I have seen it where the the wrong side or the marker lights all flash because the ground is no good and the ground though a greased ball is not as good, Going down the road they would work at times then work wrong.
:exactly: Sounds like a bad ground on the trailer. You should be able to hook up the trailer light connection to the truck without the trailer being hooked up to the truck and all the lights should work properly. Do NOT trust the ball being your ground.

A test light used on the 7-way will check conferm all circuits working from the truck.
 

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ya back up to the trailer and plug it in but don't put the tailer on the ball the lights should work if not you need to add a ground from the trailer to the connecter i had to do that to my gooseneck the guys used the ball as a ground but the way my hitch is set up it isn't a good ground and some times the lights would flicker
 

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Discussion Starter · #8 ·
Found the problem. It was a bad stop/tail/hazard module located behind the fuse block. i did some searching around on here an happen to find another member (BlackMax Canada) was having the same problem and the module was causing his light to do all kinds of weird things.
Got a new module for the local dealer ($70) and now everything is back to normal.
thanks for all the help.
 

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that is good that you found it. i hate trying to find problems in wiring
 
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