P3 Brake Control Switches from Trailer Connected to No Trailer Connected on 2004 Land Rover

Question:

I have just installed a P3 brake control on my 2004 Land Rover Discovery II. I have yet to buy a trailer but expect to in the next month. When I come out in the morning or any time after the P3 brake control goes to sleep mode, and I turn the car on, the screen shows as if I have a trailer hooked up. The power changes as I stop and go. When I turn the ignition off, the screen goes to the alternating screen No trailer Connectioninch and then to the Tekonsha home screen. If I turn the car back on before it goes into the sleep mode, the No Trailer Connection screen will come on and then change to the Teconsha home screen. Is this correct? Shouldnt the No Trailer Connectioninch come on everytime I turn the ignition on no matter what? When I received the P3 unit, the box was torn and everything seemed to be repackaged. Im concerned that I got a returned unit that doesnt work properly.

asked by: Randy N

Expert Reply:

If an item gets returned it will go back to the manufacturer. We do sometimes have to go out to the warehouse and open up stuff to verify contents or answer a customer question.

Since the P3 brake controller is going back and forth telling you a trailer is connected/not connected that indicates a probable short somewhere. The most likely cause is a dirty or corroded trailer connector on the vehicle (we can eliminate the issue being a trailer since you aren't towing a trailer when this occurs).

Check the 7-Way connector on your 2004 Land Rover Discovery II and make sure that it is clean an free of corrosion inside where the wires attach and outside on the pins. You can also inspect the wiring under the vehicle (as much as you are able) and fix any broken, pinched, or otherwise damaged wires.

I have included some links on testing and troubleshooting brake controllers for you.

expert reply by: Michael H