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Discussion Starter #1
My “new to me” 2018 is having issue w trailer brakes. The plug on the bumper doesn’t work. Hooked up a multimeter to it and confirmed. No brakes. Everything else ok. If the plug in the bed is plugged in, it gets voltage. And the interesting thing is after that happens then the one of the bumper gets voltage too! So somethings wacko on the truck.

Thoughts?


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What exactly are you testing with your multimeter? If there is no power on the positive pin, I would disconnect the connector behind the bumper right where it goes into the plug, or a little further back in the wiring harness there is another big plug where it splits to go up to the bed. Check both of those that they are connected correctly.


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Discussion Starter #3
Testing for power. Connecting to the ground and brakes.

I can’t be a wiring issue. It works fine if you fake the truck out. In other words if I plug-in to the plug in the bed then the plug on the bumper gets voltage and stays hot until the truck power is recycled. Gotta be a computer issue I’d think?


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The first thing I would do is to examine the wiring and understand the circuits involved and see if they have power and grounds. Power and grounds is always the 1st thing to check for electrical problems. Is your trailer EOH or straight electric brakes? You have trailer lights when connected to bumper only? Have you tried connecting your truck to a different trailer with same results?Is the bed receptacle a factory unit or aftermarket unit? If aftermarket, carefully check the wiring of that circuit. I believe the ITBC system is looking for a specific range of resistance to detect that a trailer is connected. Maybe that happens when your truck has a connection at the bed plug but not the bumper plug.
 
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Discussion Starter #5
The first thing I would do is to examine the wiring and understand the circuits involved and see if they have power and grounds. Power and grounds is always the 1st thing to check for electrical problems. Is your trailer EOH or straight electric brakes? You have trailer lights when connected to bumper only? Have you tried connecting your truck to a different trailer with same results?Is the bed receptacle a factory unit or aftermarket unit? If aftermarket, carefully check the wiring of that circuit. I believe the ITBC system is looking for a specific range of resistance to detect that a trailer is connected. Maybe that happens when your truck has a connection at the bed plug but not the bumper plug.
Electric brakes

I have tried multiple trailers. Same issue.

Bed seems to be aftermarket.


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So the way the ITBC works is that it only applies power to the trailer brake circuit (while braking, obviously)after it detects that a trailer is plugged in. There’s no way to get power on your brake (Blue wire) Circuit unless it has detected a trailer attached. So it would make sense that you can get power on that circuit after you have plugged into the top plug. Have you tried it the other way around, testing the top plug after plugging the trailer into the bottom plug?

Also, another note for reference. The ITBC Will not apply the trailer brakes if you’re sitting still, and depressing the brake pedal, only if it detects that the truck is still rolling. You need to utilize the hand control if you want to apply them while sitting still.


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Discussion Starter #7
So the way the ITBC works is that it only applies power to the trailer brake circuit (while braking, obviously)after it detects that a trailer is plugged in. There’s no way to get power on your brake (Blue wire) Circuit unless it has detected a trailer attached. So it would make sense that you can get power on that circuit after you have plugged into the top plug. Have you tried it the other way around, testing the top plug after plugging the trailer into the bottom plug?

Also, another note for reference. The ITBC Will not apply the trailer brakes if you’re sitting still, and depressing the brake pedal, only if it detects that the truck is still rolling. You need to utilize the hand control if you want to apply them while sitting still.


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This was very helpful. I ended up cleaning the terminals really good with a stiff wire brush and it is resolved. There was some corrosion on some of them. Thanks to everyone!


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This was very helpful. I ended up cleaning the terminals really good with a stiff wire brush and it is resolved. There was some corrosion on some of them. Thanks to everyone!


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Glad your issue is resolved.
Thanks for giving us an update!

(y)
 
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