Dim lights with trailer plugged in?

[love2fish4ever]

Ok Doc, here's where it hurts!

The truck is fine, but when I hook it up here is what I got:

Brake lights only: Leftside - dim Rightside - BRIGHT

Headlights only: Leftside-BRIGHT Rightside-dim

Side markers are on & fine

Brake & headlights same time: L-Bright R dim again

Left signal: extremely weak (like you can barely see it)

Right signal bright & works fine

What do you think this could be?? Thanks L2f

[Jeremy airjer W]

Lets start with the year make and model?

Just to make this clear, The vehicles lights work perfectly fine in every way with no trailer connected?

Does this have a factory harness or and after market plug and play harness, or a home made (butt connectors and scotchlocks) harness?

Do the lights on the trailer work?

It sounds like for what ever reason the trailer might be grounding through the right side of the truck. I would jump a wire between a good ground on the truck to a good ground on the trailer and see if this corrects itself. It it does I think you need to take a good look at the ground wire on the truck side.

[Scott K]

I would either say a bad trailer ground, or a shorted bulb. If hooking a new ground to the trailer from the truck doesnt fix it, try hooking the trailer to a different vehicle to see if it reacts the same, if it does then you either have a shorted bulb, or a wire.

[love2fish4ever]

99 suburban 98 shorelander trailer ( not a fan of the light assembly you just push up in there)

Yes the lights work on the truck.

i believe after market plug & play

I don't have another vehicle to test the trailer, but I do believe they work. I've also had the fuse blowing senerio, but with no consitency to put a finger on things. Mine was mostly brake lights (fuse)

with the info you gave me I'll start the process of elimination. Thank you very much for your help guys!

L2f