Trailer hitch wiring

[MandRautomotive]

Hey guys. Have a question from a customer that i would like your input on. I put the backlight on my Bronco and wired it up to the hitch wiring and now the car shows that I have a trailer hooked up and has turned off my backup sensors off.

Wiring
Hooked up reverse light to #7 wire.
Ground wire to #1 wire.
Brake light to both #5 and #6 wires.

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[RagnarKon]

So what’s the question?

 

[2020FordRaptor]

So what’s the question?

Why it senses there's a trailer when there isn't.

 

[RagnarKon]

Why it senses there's a trailer when there isn't.

Oh.

It’s cause TRM module detected a load on that circuit once the lights were plugged in. Which is exactly what the TRM is supposed to do, it’s working as intended.

To my knowledge there is no way to change that behavior without reprogramming the TRM. The 4-pin connector may not have that load detection on it though… maybe… not sure. So that may be a viable workaround.

 

[JMB]

Why it senses there's a trailer when there isn't.

-Guess-

"Brake controllers send a small amount of voltage along the brake output wire, if a trailer is connected, the magnets in the brake assemblies [OR your "Backlight"] will create a power draw. This power draw tells the controller that a trailer is connected."

If you have a power draw off of 5/6 ...the controller may think you have a trailer connected and kill your backup sensors (as they would not function correctly if a trailer was hooked up)

-End of Guess-

 

[JBowles]

Yeah the trailer detection is done sensing an electrical connection on the trailer connectors, the module is seeing the load of your back up light and making the determination that the trailer is connected

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