How to Wire a Brake Controller on a 1991 International Truck

Published 08/04/2009

Question:

I have a 1991 internatial truck .I hook black wire to hot ,white to ground red to peddel n/o grey wire blue to trailer as soon as I hook blue wire up green light comes on I push on brake peddel and never see red light and brakes dont come on Seems like blue wire is hot all the time why? thanks waiting for your reply Tom

asked by: Tom

Expert Reply:

It sounds as if you need to use a circuit tester, part # PTW2993 if you need one, and be sure you have the red wire from the brake controller connected to the cold side of the brake switch. The wire you need will not have power until the pedal is pushed activating the brake light circuit. Sometimes there are many wires at the brake switch to perform various functions such as cruise control and there can be constant voltage either 12 volt or reduced and then 12-volt when the pedal is pushed, and these circuits will not work with the brake controller. When testing the wire will have no voltage until the pedal is pressed.

Does the brake circuit work when you use the brake controller's manual lever to apply the trailer brakes? If you have constant power at the trailer connector or trailer brake wiring and you are spliced to the correct circuits, you may have the power set all the way up or level adjustment set improperly and that is what is causing the power to be applied. You would then only need to adjust the trailer brake functions on the brake controller itself. Using the instructions (see link below) adjust the brake controller starting with the level adjustment and continuing through fine tuning. Remember that the vehicle must be moving for the brakes to be applied with this type of brake controller.

expert reply by: Robert G