So while mounting my backup camera, I noticed on the umbilical cover there is a tiny diagram of the pins. After reading about some other user complaints about the system going off while backing with a trailer attached, I had an idea for a way to disable the backup sensors ONLY when the trailer umbilical is connected.

I was thinking there should be a way to disable the system automatically. If I understand the wiring diagram right, there is a ground pin, a reverse light pin and the standard left/right/brake pins.

The lights are standard, but if you forget to turn on the lights or for some reason can't (alternator dying, etc.) it wouldn't work.

The hot pin (1 o'clock position) has promise, but wiring it in before the pin would mean it would always be hot and always trigger the shutoff.

The reverse light pin (center pin on my diagram) won't work since any time the umbilical ISN'T connected, the signal would turn it off (leaving it off all the time).

The GROUND pin I think is the way to go...only having current when something is connected and on - trailer lights, brakes, reverse, etc., and should be connected in some way on the 7 pin and 4 pin adapter (hopefully not separate grounds).

Now, if I use a 5 pin relay, I should be able to use it in the 'off' position to keep the backup sensor working as usual, but when in the 'on' position I should be able to take the 12v that would power the beeper to a pin I leave empty.

Here is a diagram of what I'm thinking:


This pic shows the relay in the 'off' position (nothing connected to the 7 pin or 4 pin adapter)...any time you shift to reverse and the sensors go off, the circuit is complete and allows the sounder to work.

Once you connect the trailer umbilical, I think that on the 7 pin the hot lead (charges the trailer batteries, etc.) would complete the circuit and trigger the relay, shifting the power away from the sounder into an empty pin (breaking the sounder circuit, muting it). If the 4 pin is used (and they are on the same ground), the lights would have to be on or the brake pedal depressed, but it should still work.

All of you electrically inclined folks out there...do you guys think this would work?

 

Robert,

Have you done this yet?

 

No, not yet.