Trailer wiring

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Aug 16, 2005 | 03:03 PM

redcedar

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Joined: Sep 2004

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Trailer wiring

I have a '92 Ranger. I bought a new wiring harness (4-pin) and hooked into the system with a brand new set of trailer lights.

Now, all the trailer lights work fine when the main vehicle headlight switch is OFF but if I turn the headlights ON then the trailer brake lights don't work - they go out completely - while the signals and flashers work fine.

I was informed this might be a grounding problem so I hooked a jumper cable from the truck to the trailer frame to test. Still no trailer brake lights.

(I might also add, that if my truck is turned off and there is no key in the ignition I can turn the headlights on and the radio also comes on. This doesn't seem right. Could this be affecting the trailer lights?)

Aug 16, 2005 | 09:54 PM

Franklin2

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Joined: Jan 2001

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From: Virginia

Quote:

I was informed this might be a grounding problem so I hooked a jumper cable from the truck to the trailer frame to test.

This is still not a guarentee that the lights are properly grounded. Did you scratch the paint off where you mounted the lights? Do the lights have a seperate ground wire by chance? Take a testlight, and hook to the wires at the rear of the trailer. Make sure you hook the ground of the testlight to the light housing. If it's not grounded properly, the testlight will not light.