Trailer Light Help

Strickms

Recruit
Joined
May 1, 2016
Messages
1
I have a trailer with a flat 5 for my surge brakes. If I plug the trailer into my truck everything works properly until i drop the trailer onto the ball. Once I do all lights go out and brakes do not disengage in reverse. If I take it off the ball they all come back on.

I tried two vehicles with the same outcome, also used two different balls/receivers.

This tells me its the trailer, but what? Im confused since it works when the trailer is off the ball.

Help Please!
 

Gibsonman2005

Petty Officer 3rd Class
Joined
Aug 23, 2014
Messages
75
This is an issue that is way outside my wheelhouse, but it sounds like you have a ground problem. To my knowledge the ground happens when you put the trailer on the ball. Start at the harness and work to the tail lights and make sure everything is in good condition.
 

GA_Boater

Honorary Moderator Emeritus
Joined
May 24, 2011
Messages
49,038
Welcome aboard.

Has it ever worked?

Verify all the wires from the plug on the trailer to each light and reverse lock-out are wired correctly. It seems like you may have crossed one or more.
 

redneck joe

Supreme Mariner
Joined
Mar 18, 2009
Messages
10,200
This is an issue that is way outside my wheelhouse, but it sounds like you have a ground problem. To my knowledge the ground happens when you put the trailer on the ball. Start at the harness and work to the tail lights and make sure everything is in good condition.
Welome to the forum and what he said
 

thumpar

Admiral
Joined
Jun 21, 2007
Messages
6,138
Try using a voltmeter to see what is going on. It sounds like when the trailer grounds to the ball it is messing up. Try measuring the continuity of the ground on the truck side and trailer side for continuity to there respective parts with them separated.
 

fhhuber

Lieutenant
Joined
Jun 19, 2014
Messages
1,365
you are grounding a "hot" lead somewhere on the trailer... probably the brake lead.

The surprise is that its not blowing the affected fuse.
 
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