Correct Brake Wire for Tekonsha P3 Brake Controller in 2001 Toyota Tundra

Question:

I am installing the Tekonsha P3 brake controller in my 2001 Toyota Tundra V8 with ABS and cruise control. I watched the video where it recommends the green wire with white stripe and silver dots. I located that wire and found 12 volts when the brake pedal is pressed. My question is this, in the box with the P3 was a supplemental page referring to late model Ford and Mercury trucks that described a red wire that went to ground when the brake is not depressed but had 12 volts when the brake is depressed. On my Tundra, the green wire with white stripe has these same readings. When the brake is not depressed I read straight to ground but when the brake is depressed, I get 12 volts. I really am concerned that I will ruin the P3 if I use this wire. Do I need to find another wire that comes directly off a brake light and wire back to the controller or can I safely use the green wire with white stripe? Thanks for your help!

asked by: David R

Helpful Expert Reply:

I verified with Tekonsha that you have the correct wire. It's the cold side of the stoplight switch which will give you 12 volts when the brake pedal is pressed. The ground reading you're getting is from the light bulbs themselves. The P3 # 90195 doesn't actually draw amperage from the wire it only uses it for signal to know when it needs to engage your trailer's brakes.

The warning you're referring to on some Ford model trucks is a wire connected to the cruise control and goes directly to ground when the pedal is not depressed.

expert reply by: Charles S