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Discussion Starter · #1 ·
Is there a way to figure out if my control is not working, or the trailer brakes don't work. When hooked up I have no lights or any indication that a trailer is there. This is brand new prodigy, I cut the wires from the vouager and replaced it. Its been a long time since I hooked up to this trailer. (its my brothers dump trailer) I have no other trailer to test on. Here is what I have checked and done.

Blue wire is connected right through to 7pin. checked with ohm meter.

red wire gives me full power at the controller when the brake is pressed.

White wire is grounded.
black wire cannot remember what its for. No power or ground.

The wires in the trailer 7 pin are nicely conected and the end is brand new.

How might I check that he didn't reverse the brake wire and ground on the trailer. If ohm meter the connecter everthing shows a short to ground even the lights. Which all work perfectly.
 

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All around nice guy
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52 Posts
IIRC, black is power to the controller.

Lights should show as a short to ground, unless they are LED. They are very low impedance...
 

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Fill Diesel Only
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1,031 Posts
Discussion Starter · #3 ·
Thanks, I have no power at black. wonder if a fuse blown.
 

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5,957 Posts
There are a couple fuses for the trailer controls in your fuse box...
 

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124 Posts
There are a couple fuses for the trailer controls in your fuse box...

Any idea which fuses they are?? I am in the same boat as this guy...
 

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398 Posts
im going to be wiring mine up tonite....here is a diagram im going to use....correct me if this is wrong in any way before i go splicing wires...

 

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I have a GMC Sierra and I think the trailer brake fuses might be blown.....can you help?
This has been for 3 trailers now. It cannot be the trailers with this many. I am wondering if it is my truck.
 

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Premium Member
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101 Posts
You can buy plug testers, they plug into the truck connectors and have led lights that light up to tell you if your controller and brake, turn and clearance lights work. Also check your ground, most trailers ground through the ball and don't always have a good connection.
 
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