Why Would Prodigy Brake Controller Show Voltage Display At all Times

Question:

I am using a 2004 Porsche Cayenne turbo with the factory Tow Module most recent G revision part number. It has a factory-wired brake controller plug under the dash, which I wired up to. Everything works fine except that, when the brake isnt applied, the display doesnt always show 0.0V. Sometimes it will stay at 0.0, but it often fluctuates between 0.2 and 0.5V while cruising down the highway, and if I am accelerating hard like for merging, I can feel the trailer brakes pulsing a bit and holding the car back. I have turned down the max voltage to 8V and am not using boost and it works okay, but Id like to get the controller to not actuate the trailer brakes when Im not braking.

asked by: William

Expert Reply:

That is a pretty interesting problem you are experiencing that has to be related to the stoplight circuit wire (red) that you used for the install. Use a circuit tester like # 3808 to test the wire you used for this wire to verify it's voltage. It should only see 12 volts when the brakes are applied, but it sounds like yours has voltage on this circuit at all times.

You need to find a circuit that only sees voltage when brakes are applied.

expert reply by: Jameson C