wiring problem Truck/trailor

[Turfcutters Plus]

I have a 96 gmc with trailor hooked up.All lights work except when i turn headlights on,there is no trailor lights in back of trailor.Also,no longer do headlights on truck come on by themselves(Safety feature)during day in normal operation.My other truck with same trailor works fine.I've narrowed it down to 96 gmc problem.What do i do to fix it?:confused:

[Turfcutters Plus]

Also,brake lights and turn signal lights work fine on back of trailor.It's when i turn headlights on,it kills tail lights.

[fixer67]

With the trailer unpluged does the truck lights work as they did before you rewired for the trailer? See if you can get our hand on a copy of The Pocket Ref 3rd Edition (ISBN 1-885071-33-7).
I tried to scan a few pages for you to see but they did not come out readable.
On pages 42,43,44,45 you will find the standard trailer wiring data.

[UNISCAPER]

Do you have one of those slide in trailer recepticle harnesses that comes pre assembled? They go bad occasionally. Try omitting that harness by connecting the one side of the rear lights to the other. If everything works, you got a bad harness.

[Turfcutters Plus]

Thanks guys.I fixed it.Corroded wire that was spliced together.:rolleyes: