ground problem ?

[two cups]

I own a 2006 GMC pickup. When I hook it up to a trailer the running lights work, but when I turn on the blinkers the running lights blink also. When the brakes are on the running lights go out. I wired the trailer lights to a battery and they worked fine. I bought a round 7 prong to flat 4 prong adapter with lights on it that is supposed to check the trucks wiring system. Lights don't come on or one might lightly. Has any one else had this problem. Any help would be great. Thanks, Rick

[SkunkedAgain]

In my experience that is a grounding problem 90% of the time. Take a spare piece of wire, turn on the blinkers, and then touch the wire from each blinker to the frame. As you move around the trailer testing each blinker you should find one that makes the whole system work when you touch the ground to the frame. Once you've isolated the light you can try to find where the ground is failed...or just run a permanent ground.

[Jeremy airjer W]

I think your on the right track also 2 cup!

Does it happen with any trailer, just one trailer or you don't know?

If its more than one trailer its probably on the vehicle side of the wiring. If its only one trailer that you can focus on that trailer.

[rundrave]

what type of trailer?

I have an older tilt bed trailer and had grounding issues. Essentially what my problem was that the tilt bed trailer is really 2 different pieces, trailer was grounded on the bottom frame that didnt tilt, but the lights etc were on the top part that tilted. Once I had a good connection between both pieces of the trailer life was good.

just another thought, I could be way off, but I read the sticky posted trailer lighting thread and someone had suggested that there, and it worked for me.

sometimes its super easy things to over look that will make the lights not work right.

[two cups]

It is on a new fish house that I bought. Do not know if it does this on different trailers. When I got the house I kept blowing fuse's, found that they wired the clearance lights wrong (wire ground to hot). So I wired the whole thing over and even ran a seperate ground with to each light. When I check the lights on the fish house using just a battery and no truck the running lights, blinkers, and brake lights all work right. So I decided it had to be my truck now, so the easiest thing to do was to buy a new 7 round to 4 flat adapter to see if mine was bad. They had one that had lights on it that should light up if the trucks wireing is good. Mine adapter did not light, so I think it has somthing to do with the truck. It has been a pain, and I don't want to finish the inside of the house till I am sure they work. All lights work on my truck so I think it has to be the ground in the trailer harness????. Thank You, Rick

[SkunkedAgain]

Trace the wire harness. Usually the wires run from the harness to your regular truck wires. There might be a wire that has seen better days.

[opsirc]

sounds like a ground, but I have also had problems with adapters not working right.

[muddpuppy]

I have an 03 silverado I had the same thing and it was the Flasher modual the was bad. It's a all in one fuse for the lights spendy part I am almost positive it would be the same part/wirering as in your trouck

[crothmeier]

i have a problem right now with my pickup and have narrowed it down to the "plug" at the back of my truck. i wiggle the wire going into the back of that plug and the lights flicker.