Trailer brake lights go out when brake is applied

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  #1  
Old 09-25-13, 05:17 AM
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Trailer brake lights go out when brake is applied

Ive rewired a 16' trailer, I have 2 lights behind the wheel wells and 2 at the back.
When I apply the brakes the 2 lights at the rear go out. Ive seen this qustion before but havnt found an answer. Thanks for any help.
 
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Old 09-25-13, 05:58 AM
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Its eaither wired wrong or a ground issue from what I know.... How is it wired to the tow vehicle? with a 4 pin?
 
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Old 09-25-13, 05:59 AM
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Looks to be a grounding error, or a wire swap. Make sure you have the ground wire on each light connected to the white wire and make sure you ground not only the chassis of the trailer, but run the white wire completely to the pigtail and ensure the truck/car ground is attached to the truck/car chassis. If the ground is not attached to the proper wire it will result in positive grounding, which you don't want.
 
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Old 09-25-13, 06:22 AM
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im running a 4 way all the way to the rear and have the wheel well lights tapped into it. All other lights work on all 4 lights (running and turn) and the brake lights work on the wheel well lights. there are only 2 wires coming from the rear lights black and green. Im assuming black would connect to the brown (running) and the green to either the green or yellow (left/right turn). Dont have a white wire coming from the rear lights. I have it grounded at the front of the trailer where the 4 way starts to the side with a self tapping screw. This trailer does have brake assistance but my truck is only wired for a 4 way so i bypassed the blue wirer and not connecting it.
 
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Old 09-25-13, 06:26 AM
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In direct current, black is a ground, so swap the black and green on the rear lights to see what happens. There are only brake lights in the rear ones, right?
 
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Old 09-25-13, 06:42 AM
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The rear lights, are brake running and turn. I swapped the wires last night and nothing happened. I tightened the bolts from the light to the trailer and swapped the wires again, and now I think its working. May have been a bad ground from the light to the trailer? Thanks for the help guys! Next beer is on me...
 
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Old 09-25-13, 08:26 AM
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Glad you got it fixed. It seems the ground is the most prevalent problem with trailer wiring. Bad or loose ground and nothing works right.
 
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