Trailer hitch reverse (5th wire) wiring question.

[richone52]

My trailer has a 5 wire setup and the 5th wire is for reverse. This allows the trailer to disengage the brakes. I was testing the wiring and I see that the 5th wire only flashes on for a second and then goes off (with a tester). Does anyone have this type of setup with trailer? If so, Shouldn't the power stay on so the brakes stay disengaged? Before I bring it it I need to find out for some of the other people with Trailer option as my dealer is not very up on trailer and the hitch option.

Thanks

Rich

[X5Dawg]

Do you have the factory wiring harness or an aftermarket??

[richone52]

It is a dealer install and the BMW option with the Factory wiring Harness. I should also add that it is a 5 wire set up for reverse not 4 wire. The 5th wire is the reverse line.

[X5Dawg]

I agree with you - there should be constant power on that circuit to keep the brakes from reactivating.

[richone52]

Thanks ... I agree. Does anyone with the Hitch actually know if this is how it is functioning?

[tetonguy]

I have a 2001 X5 with a factory hitch and the round seven blade plug connector. I also have a boat trailer with brakes which uses the 5th wire solenoid lockout when backing the trailer. The 5th wire is always at 12volts when the standard tranmission on my X5 is in reverse. It is connected to the backup light circuit. If you have an automatic transmission it may be connected differently. If so just run a wire from the backup light to the harness. Hope this helps.