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lj2654's avatar
lj2654
Explorer
Jan 19, 2017

Wiring a DP for towing a toad

I have been having issues with my wiring on my 2001 diesel pusher for the plug for towing a vehicle.

I have to use a 3 to 2 wiring converter as the coach has separate turn and brake lights and the 2012 Cadillac SRX has single brake and turn led lights.As soon as I think it is correct I have an issue with the lights not working once again.

The 3 to 2 converters are going bad. Now I have just replaced one again and am having issues doing the wiring and getting it working right.

I know the car is correctly wired as a tech has rechecked it with me and said it is right and its a wiring issue with the RV. Where do I start to figure it out?
  • The MH isn't already wired with a 7 way trailer connector?
  • I too would assume that you have a standard 7 blade trailer light connection. So here is what I would do which can also be done with a flat four coming from the RV.

    Remove all the convertors and add on stuff between the RV's stock harness and the socket. Now you're back to where you were when you bought your rig.

    Buy and install two separate sockets for the turn signal cans and wire your flat four, right and left turn signal wires to those lights. You will also have to install two more diodes for those lights.

    If you buy a new towed and it has combined parking/brake lights, your good to go, if it has the separate brake/parking lights you just buy two new sockets and install them in the brake light cans. Simple and only two very simple and "reliable" electronic devises to install, the two additional blocking diodes.

    If you are like me and use another vehicle that I use to tow the Sidekick with flat four wiring, it's good to go.

    You have just had an example of K.I.S.S method applied to your problem.

    PS; Nice rig, a couple we met fell into a deal on a Beaver, owner died, wife sold it for the balance on the loan, $103,000. Nice.
  • It is wired already with a 7 pin round plug, but lights are dim and sometimes are difficult to get to work...
  • What supplemental brake system do you have?

    Do the brake lights on the towed come on when the ignition is off and you step on the towed brake?
  • lj2654 wrote:
    It is wired already with a 7 pin round plug, but lights are dim and sometimes are difficult to get to work...


    That is exactly why I suggested removing all the add on converters. :W

    I have found that those 3/2 converters are not always a trouble free as they advertise.
  • Got it straightened out, I removed everything and started from scratch. Should have done that from the start I guess. I found that the tail light wire was hooked up with the ground wires for who knows why. Now I have it all hooked up with a lot less coiled up unneeded wire. Looks more professional now and everything works as required finally.

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