I have a 2005 Ford Excursion. It has a parking sensor which beeps when it senses something close to the rear bumper. When pulling a trailer, it beeps every time I put it in reverse. I can turn it off, but it turns itself back on each time I shift into reverse.

My brake controller wiring harness knows when a trailer is plugged in. I would like to tap into this wire, and when it is hot turn off the parking sensor. When I don’t have the trailer, I would like the sensor to work as normal. I prefer not to have a rocker switch because I will often forget to turn it on/off.

What is the name of the component I’m looking for? I want the parking sensor wire to be closed when the input is 0V, and open when the input is 12V.

  • 1
    What are you going to disconnect with your switch. If you just disconnect a sensor, then some reversing warning systems will bleep at you each time you select reverse to indicate that the sensor is faulty.
    – HandyHowie
    Apr 26, 2021 at 9:09
  • That's a great point, @HandyHowie. I was planning to install this right next to the on/off for the parking sensor, and I want to mimic pressing the on/off button for the sensor. I haven't looked at the wiring yet to see what's available, but I'll be sure to test so I don't make the problem worse. Apr 26, 2021 at 14:48

1 Answer 1


A relay will do what you want.

Get one with 5 terminals as that has contacts changing to “open to closed” and “closed to open” on power, and that is the functionality you want.

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