Cant Find Right Brake Switch Wire to Install Brake Controller on 2003 International 4400

Question:

I have recently got a p3 tekonsha electric trailer control unit, I have been trying to hook it up to a 2003 international 4400 with air brakes. I have hooked it up like the instructions said but its not working properly and I dont understand what I did wrong, ive gone to the brake switch and tried to test which wire is the cold end but when I use the test light, nothing lights up. how could I wire the brake switch wire properly without putting it to the brake switch? and last question does this brake unit stay on all the time?

asked by: Keith

Expert Reply:

Truck with air brakes such as your 2003 International 4400 do not necessarily have the proper wire at the brake switch. It does sound like this is the case on your truck. You can check the fuse panel for the stop light or CHMSL fuses. As long as the stop light or CHMSL fuse is the only item on that fuse you can tap into that circuit using a fuse tap.

Or, if the truck has rear brake lights on their on circuit and not tied into the turn signals or running lights you could tap into a brake light wire.

The P3 brake controller will go into a low power standby mode after about 15 minutes of sensing no activity.

expert reply by: Michael H