2017 Ram 3500 Trailer Lights Stay on With Truck Off

Question:

So I had my right trailer light staying hot all the time through the signal prong even when the truck was off and the signal was not working so much as to it melted my trailer plug so I pulled the F30 fuse and everything thing is working fine now. What would cause this to happen

asked by: Matt

Expert Reply:

It sounds like there is a short or something is mis-wired. I recommend using LCD Digital Circuit Tester # PTW2992 and testing the functions on the trailer connector on your truck (you will need to put the fuse back in place) and seeing if you are getting constant power on the right turn signal terminal.

There is a good chance that corrosion built up inside the connector, and the Aux power terminal is crossing over to the turn signal terminal. The 2 terminals are right next to one another so this seems very likely. I suggest taking the 7 way apart, inspecting and cleaning the terminals and then apply some dielectric Grease # 11755.

If there is no signal with the lights off, then more than likely the issue is on the trailer side. If your trailer has a separate battery, make sure it is not connected to the tail light wiring (corrosion in junction box). Also check to make sure all of the grounds are secure and attached to bare metal surfaces free of dirt and corrosion.

expert reply by: Robert C