Help, rear lights all messed up.

[Rum Runner]

I installed a tailgate salter on my 2001 GMC 2500HD 6.6. my lights were all working proper. I ran the power for the salter from the battery through the firewall by that big elect box on the floor in front of the emer. brake up to the salter controller. The salter power wire was installed along the frame rail with the factory wire loom to the rear of the truck. When I left the shop, when I applied the brakes the back up lights came on .
The lights on the front of the truck all work proper. the running lights work proper front and back. when the haz lights are on the running / sig alternate, and the rev lights come on and the lights are dim. I bought a new light cont modual for the back but still acting up. all fuses are good.
Any suggestions......HELP.:confused:

[DickWells]

I'm no electrician and you'll no doubt get some solid advice from those who are, but, to me it sounds like the same old problem that you get with trailer lights. Bad ground somewhere? Don't know how many times I've found that problem on my own, and other's rigs. Cross-talk between/among the rear lights is the most common sign, along with dim lights. Still, I'm not sure about your power source, either. Without looking at my own rig, I can't really visualize the location for that power take-off point. Willing to bet that one of the more savvy guys, or gals will be on here with a solution for you, forthwith. Meantime, make sure that you have a solid ground for everything. Good luck.

[DmaxMaverick]

It does sound like a ground issue. Either you've lost a ground, and the circuit is grounding through another terminus, or your new wiring has created a "new" ground.

I suggest undoing everything you did, and rewire, but keep it simple. In the same panel you "sourced" your power for the salter, is the trailer brake control. Use that circuit for power. If you have the OEM brake control harness, it has Batt+ power, and a heavy lead (12 or 14 awg) that goes to the trailer connector. If you use trailer brakes, you could wire a bypass switch into the harness (to power the salter), and use a trailer connector to connect the salter to the truck. It should be a simple and clean solution.