Troubleshooting Installation/Wiring A Tekonsha P3 On A 1998 Toyota Tacoma

Question:

Installed the P3 on my 1998 Tacoma. Pretty sure I chose the correct stop light wire to connect the P3 red wire to—the one that only has voltage when brakes are applied. After test driving with trailer attached noticed that cruise control doesn’t work and the P3’s readout shows voltage being applied even when I’m not applying brakes.

asked by: Mark

Expert Reply:

If the cruise control has been disabled, it is likely not connected to the correct wires. I cannot say I have heard of this particular issue before with the cruise control, but were the controller wired correctly, it would be working as normal. You certainly should not be getting a constant 12v. At this point I recommend going in with a wire probe like # PTW2993 and test your brake switch. The wires on the P3 # 90195 will be connected as follows.

Blue: trailer brakes
White: vehicle battery negative terminal
Black: vehicle battery positive terminal
Red: cold side of stoplight switch

expert reply by: Jesse M