Troubleshooting Blue Wire on Trailer Brake Controller Always Getting 5 Volts

Updated 06/17/2019 | Published 06/14/2019

Question:

Why does the blue wire on my controller have 5volts all the time. I tried a new controller same problem

asked by: Doug

Expert Reply:

The blue wire coming from the back of a trailer brake controller like the Draw-Tite Activator # 5504 that you referenced will always have some type of minimal voltage on it, but it should be more of a pulsating power and not constant. This is basically the controller's way of looking to see if a trailer is connected.

While 5 volts is a tad higher than what is typically seen, if the voltage you mentioned is pulsing and not constant, then this isn't a problem as long as everything is working correctly.

If you are getting a constant 5 volts though on the blue wire then I first recommend testing the controller itself. I know you recently replaced it but it will still be best to rule it out as the culprit. Sever the blue wire a few inches away from the controller and test it again. If it's still getting this constant voltage then there is an issue with the brake controller itself and it should be replaced.

If this constant voltage isn't present when testing it in this manner then there is some kind of short on the blue wire between the controller and the trailer. Inspect the wire along the vehicle for any exposed, pinched, or damaged areas that need to be replaced. Inspect the 7-Way both on the vehicle and trailer for any debris or corrosion inside the pins that needs to be cleaned out.

If you still aren't able to track down the issue please let me know and we can continue to troubleshoot.

expert reply by: Chris R