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Old 01-29-2012, 03:11 PM
Stale Trooper Stale Trooper is offline
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Like many others, I think you're making a mountain out of a molehill. I have built 2 testers; one for my camper which utilizes the on-board battery of the camper to run the lights via the 7 pin RV plug. I put my back up lights on the center pin. In the attached drawing, I mention a single pole-double throw switch, I used the same type switch, but these are spring loaded momentary switches; either type will work, it's a matter of choice, cost, and availability. I had the switches already, so thats what I used.

The other was a simple light tester with small clearance lights that act as my camper's tail/running lights & turn/brake lights. I mounted the clearance lights on an old metal license type plate, with a pigtail long enough to let it hang on the inside of my tail gate so I can see the lights working as I push the brakes etc. The black wires you see running to each light are the power wires from the 7 pin RV Plug; the lights are grounded through the metal plate. You may notice a bulb for the trailer brakes. This won't work! The signal to the brakes is different, and I don't know how to make that part function.

These tools might have cost me $10-15 a few years ago, but I would guess them at $50-60 for the pair today.

I issue the usual disclaimer, I'm not responsible if you burn your fingers, or torch your vehicle due to your inability to work with DC current, blah blah blah.
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Last edited by Stale Trooper; 01-29-2012 at 03:17 PM. Reason: Edit photos & add diagram
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