Connecting Brake Controller to Brake Stop Lamp Switch on 2006 VW Jetta

Question:

Can I connect a Prodigy P1 brake controller to a 2006 VW Jettas brake switch? I have it connected by a long wire to the post-converter brake light now but that causes intermittent braking when the turn signal is on. It also causes erratic flashing on the display when the lights are on. Thanks

asked by: Jack A

Expert Reply:

You might be able to connect to the brake switch. Use a circuit tester like part # PTW2993 and carefully probe the wires exiting the brake switch. If you find one wire that only shows voltage when the brake pedal is pressed (but not with the running lights or turn signals) then you can tap the red wire from your Prodigy into that circuit.

The third brake light circuit might be a viable option to find a clean dedicated brake signal as well. Some of the newer VW's use Pulse Width Modulation (PWM) wiring where more than one signal is carried on a wire, so you'll want to test the wire for the third brake light to ensure you're only getting signal on that wire with the brake, not any other lighting function.

expert reply by: Mike L