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Old 07-16-2018, 02:30 PM   #3
Bobbed72
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Join Date: Apr 2017
Location: Hillsboro, OR
Posts: 80
Re: Tail light wiring.

Quote:
Originally Posted by ray_mcavoy View Post
No, there normally isn't a circuit going to the back of the truck that turns off when the brake is pushed so it sounds like you have some other problem going on there.

If the rear wiring is stock, it should have the following wire colors:

Brown = tail lights, live when the headlight switch is pulled out to either the 1st or 2nd notch. This is the circuit that originally powered the rear license plate light.

Yellow = left rear turn signal & brake light.

Dark Green = right rear turn signal & brake light.

Light Green = reverse lights.


The factory ground for the tail, brake, and turn signals made use of the metal light housings screwed to the bed which is bolted to the frame. So it's not uncommon to have ground problems due to rust, corrosion, paint, and such. And depending on which wire you tapped into, you can get some strange behavior with power backfeeding through the dual-filament bulbs when they have a poor ground.
Thanks, that helped. I connected the ground wire to the brake lights. Apparently the wire goes to ground when inactive. Hitting the brakes broke the circuit.
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