trailer lighting issue with factory tow package.

[syncro]

Hi all, hoping I can get some help here. I've got a 2003 sierra 2500HD with the tow package and a 7 pin connector and all the lights/signals work properly on the truck. When hooking up to a trailer with a 4 pin connector and the right adapter I get theses results:

 

1. no tail lights on the trailer

2. brake lights work

3. no left turn signal but +2V at that pin

4. right turn signal activates the hazards, both left and right lights flash

5. lights flash when the hazards are activated

 

 

When looking at the 7 plug on the truck and checking it with a digital multi-meter I get these results:

 

1. the left turn signal pin (9 o'clock) shows +2V at all times

2. no voltage at the tail light pin (about 11 o'clock) with the truck lights on

3. +12V at the tail light pin when the truck brakes are pressed

4. +2V at the left signal pin when the truck left turn signal is activated

5. +12V alternating/flashing at the tail light pin when the right signal is acivated but no voltage at the right turn pin (3 o'clock)

6. +12V alternating/flashing at the tail light pin when the hazards in the truck are acivated

 

 

I know it's not the trailer or the adapater because when I test it out on a buddy's Chevy with a 7 pin connector everything works fine.

 

The only thing that comes to mind is about a year ago I was having issues with my signals and sometimes the left would not work. I would have to switch the signals between left and right to get it to work but I have not had that issue for a long time.

 

Any thoughts on just what the heck might be going on here? The factory wiring looks to be unmolested at the rear but the previous owner seems to have had an alarm installed at one time. But as said, the trucks lights and signals all currently work correctly.

 

Thanks in advance ofr any help.

 

 

[jason25]

Hello, I am having a similar issue with my 2004 suburban. Im hoping i can tag-a-long on this post to get some help.

I have a 2004 suburban 1500 with a factory tow package. I just recently bought a 30' camping trialer and had the place I purchased the trailer from install a braking control system for the trailer. I picked up the trailer last month and everything was working fine when i left the dealer with the camper. I stopped at an oasis about 20 minutes from my distination and the right brake light on the trailer stopped working. Everything else works on the trailer. I know its not the trailer due to hooking it up to my father in-laws truck and the lights work. On the truck I have voltage on all the pins: except the one that controls the right break light. I took my truck back to the dealer thinking it was their equipment they installed with the brake control system, but all their equipment checks out, and all fuses are good. They said it could be the Chevy converter for the trailer lights?? Does this makes sense? I never heard of a truck having a converter for trailer lights or lights at all. Can anyone point me in the right direction on what to check? I have camping trip coming up very shortly with my family.

[syncro]

They said it could be the Chevy converter for the trailer lights?? Does this makes sense? I never heard of a truck having a converter for trailer lights or lights at all. Can anyone point me in the right direction on what to check? I have camping trip coming up very shortly with my family.

 

This sort of makes sense as the chevy/gmc products use a 3 wire system - separate tail, brake and signal lights and trailers use a 2 wire system. Worst case scenario we could just buy a converter w a 4way plug at an auto parts store and tap into the wiring on the truck to have a new plug to connect to the trailer. Personally I'd rather get things fixed properly so the factory plug works the way it's supposed to. Unfortunately I leave for a trip on Fri morning so only have one day top get this sorted out.

[diyer2]

Check with your local U-Haul if time is running out. They will fix it IMO.