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norcal10's avatar
norcal10
Explorer
Sep 17, 2013

Trailer Running Lights Issue

Hi everyone,

I recently acquired a 1979 Nomad 23ft trailer. However, I can not get any of the trailer lights to work. No running lights, tail lights, clearance lights or electric brakes. The only light that works is the passenger side turn signal. I've cleaned every light, tightened the grounds on them, cleaned the ground from the 7-way that is grounded on the trailer frame, sprayed the pigtail with WD-40, bent the prongs just a tiny bit so they fit tighter, but still the only thing that works is that passenger turn signal. Ive tested the lights with a probe tester and the only one getting power is that passenger turn signal.
Im running out of ideas. I'd appreciate any advice that you guys and gals have to offer. Electrical is not my strong point.

Thanks everyone!

15 Replies

  • You need a multimeter and some patience,along with a good 12vdc source.Locate the TT ground and go pin to pin with the 12v,and ck each lamp for voltage Also carefully look at the TT harness.I had and old friend with a Shasta that had broken rotted wiring where the harness crossed over the frame aft of the hitch.
  • Are you sure the plug on the tow vehicle works?
    Plugging in the first time could have blown fuses.
  • How are you checking the lights?

    Your trailer is kind of old and I don't think that 7 pin connectors had a universal order for the wires back then (colors may be different today as well.

    Try to use a battery with a ground on the frame and then a hot wire to the trailers plug. Test each terminal with an alligator clip or something and see what light comes on.

    Then you will see what works and what does not.
  • DRSMPS wrote:
    I would start at the 7-way connector and start following the wires back on the trailer. You'll likely run into several junction points which are corroded or loose. If you use your tester at each connection point, you'll soon find the faulty point in the circuit.

    Frustrating - I know. Kind of like finding the loose bulb on your Christmas lights!

    Good luck.


    This is correct. The only way to fix it is to start tracing wires. Good luck.
  • I would start at the 7-way connector and start following the wires back on the trailer. You'll likely run into several junction points which are corroded or loose. If you use your tester at each connection point, you'll soon find the faulty point in the circuit.

    Frustrating - I know. Kind of like finding the loose bulb on your Christmas lights!

    Good luck.