trailer lights?

greenthumb · Apr 1, 2002

Got the utility trailer out this weekend I haven't used it since last fall it's been packed away in the barn. All in good shape except I have no brake lights. I have turn singnals, and running lights but when step on the brakes with the running lights on they go out. I changed the light bulbs in both lights no help. then I started investgating. I am getting power from thesupply from the truck (by the way the truck is a chevy 1500 1995 with four three wire hook up plus my ground and hot wire for my brake control. I don't use the back up supply. when I took the light off and held the post that bolt to the trailer to the crome of the bumber on the truck they lights worked fine. I was wondering that since there is not a ground if the trailer connected to the truck acted as the ground. I have notice a lot of rust on the hitch from this past winter's salting so I am curious to ask could I have lost the ground because of this? any thoughts

s1120 · Apr 1, 2002

Yup, sounds like you lost the ground. Best thing, hard wire a ground. The hitch is not a good ground.

MossRoad · Apr 1, 2002

Sounds like a bad ground to me. The easiest way to test would be to run a wire from bare metal on the truck to bare metal on the trailer. Also, some plastic light housings must be grounded to the trailer by a wire. Sometimes the connection where this wire meets the trailer becomes corroded. Take it off and clean it if there is one.

Charlie_Iliff · Apr 1, 2002

The ground wire on the truck is the culprit. Best cure is to run a ground wire all the way from the negative battery pole to the trailer plug. Next best is to find where the trailer harness grounds to the truck frame. On my '89, it is a bolt on the outside of the left rear frame rail. Backing that out, polishing all connectors, squeezing a little dielectric grease to slow future corrosion and reassembling will do the trick.
I'd love to say I figured that out without learning the hard way. This February I had a trailer that I had wired four years ago - with separate ground wires to each light - do exactly what yours is doing, on not one, but three tow vehicles: a Suburban, a Ford Van and my Chev truck. So, I replaced every wire and light on the trailer. It did exactly the same thing. Then I fixed the grounds on all three tow vehicles, which fixed it. About 15 minutes work took me two days. Even worse, I think I did the same thing with a horse trailer 10 years ago. Think its Alzheimers?

Bird · Apr 2, 2002

Like the other guys said./w3tcompact/icons/wink.gif It's a very common problem. Sometimes just grounding through the hitch works, but not often enough for me to ever do it again./w3tcompact/icons/laugh.gif