Towed Vehicle Wiring

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Put brackets and wiring kit on the Towed Vehicle (2005 Chevrolet Colorado).  Every thing went well but:  I grouded the installed wiring harness to the Pickup bed directly behind the Tail-light (most convenient), but when I measured continuity from the White Harness wire to the Negative terminal on the battery I did not have "0" ohms.  When connected to the MH all signals worked properly but the lights on the Toad did not seem as bright as they should be, of course it was a very sunny day.  Am I in trouble.

All of the above leads to the question; "Is the Pickup bed isolated from the Frame??     

Gary RV_Wizard

Site Team
Feb 2, 2005
West Palm Beach, FL
"Is the Pickup bed isolated from the Frame?? 

Generally no, but it probably has some rubber bushings and over time corrosion can develop as well. You can easily check continuity between the bed where you gtrounded the wires and the frame underneath - just get an extra length of wire to extend your meter probes.

I'm a bit unclear on what you grounded.  When towing, the ground reference  for the toad lights is the motorhome ground, not the toad's battery.  You want a good clean ground path from the toad to the motorhome, either via direct wire all the way though or by a ground wire between toad chassis and motorhome chassis. A poor toad ground can result in dim lights or various bizarre combinations of wrong lights coming on, e.g. a left turn  signal blinking when you turn the right signal on.


The wiring harness came with four wires -- green, yellow, brown and white.  The directions called for the White wire to be connected to the frame with a Ring Connector.  It was more convenient to connect directly behind the Taillight Assembly to the bed of the Pickup. 

I realize that the lights use the power and gnd of the MH when being towed, but I made no connection to the black wires of the Tail, Turn and Brake Lights of the Toad.  Those black wires were in the wiring harness and I assume got gnded at some central location which should be common with the Negative terminal of the battery.

I will check continuity between the various componets (pickup bed, frame & battery neagative) and move the Harness White white wire accordingly.  Was just trying to save a little work and be better prepared when I go back to the Toad. 
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