Trailer lighting issues.... please help

[bizzo15]

Guys,

I recently bought a snowmobile trailer for cheap that needs some restoration. I just rewired all the lights on it and they work fine but I'm having a weird issue. All of the lights and blinkers work fine but when I turn on the headlights in the truck and put the brakes on all of the trailer lights go out. If I have the headlights off and hit the brakes the lights on the trailer work. At first I thought maybe I wired something wrong on the trailer but then I remembered I had the same problem with a uhaul trailer not too long ago. Has anybody else had this problem or know where to start looking to figure this out?

Thanks

 

[ancho]

I'd probably start with a digital multimeter to check what's being output through all the wires when different lights are being activated. It sounds to me like a possible grounding issue.

 

[Fobroader]

Check the grounds in your rear talilights. Ive seen this on a few trucks, bad ground at tailights=youre trailer being possesed!!

 

[bizzo15]

Ok, I'll have to pick one of those up. Is there anywhere else besides the very rear where the lights are grounded? I ask because my tail lights stopped working so I redid the ground connection using a test light to make sure I had a good connection.

 

[Fobroader]

The actual trailer plug itself, make sure its in good shape. The one beside your hitch

 

[bizzo15]

The trailer plug is brand new. When you say tail light ground are you talking about the the one ground that comes out of the wire loom that runs alongside the drivers side frame rail? Or is there additional grounds for the tail lights?

 

[Fobroader]

Check all teh ground that are attached to your tailight harness, Ive never followed the grounds, I dont know where they go.

 

[LUCASisCOOL]

Hey man, I actually work for Uhaul installing wiring and hitches. Your best bet is to make sure that you have the plug on the truck wired right, with the ground on the plug grounding to the frame of the truck. also if i remember correctly, there is just the one main ground that bolts to the drivers side framerail. and then make sure that on the trailer there is a good ground. most tail lights on utility trailers and boat trailers use a frame ground as the common and just have the 2 wires for the tail and stop circuits. check where the tail lights bolt to the trailer and make sure they are getting a good bite to the metal.

 

[shortchevy]

Hey man, I actually work for Uhaul installing wiring and hitches. Your best bet is to make sure that you have the plug on the truck wired right, with the ground on the plug grounding to the frame of the truck. also if i remember correctly, there is just the one main ground that bolts to the drivers side framerail. and then make sure that on the trailer there is a good ground. most tail lights on utility trailers and boat trailers use a frame ground as the common and just have the 2 wires for the tail and stop circuits. check where the tail lights bolt to the trailer and make sure they are getting a good bite to the metal.

I work for a similar company and agree its the truck, try the trailer with a different truck to rule out the trailer. If the ground ends up being bad throw a star washer in.