Installing Brake Controller on 1990 Ford F250

Updated 05/09/2015 | Published 05/08/2015

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Question:

I have a 1990 Ford F250 with the towing package but I have never needed to use it until now. I have the factory harness with the jumpers but they state that the 3 wires in the cab are: RED from the battery, RED-green stripe for trailer brake lamps, BLUE for powered trailer brakes I understand that your controller has a white wire for ground black wire for battery power Is your blue wire for powered brakes and your red wire for brake lights? I read on your site that red wire was for cold side of brake pedal switch so I am a little confused. Thanks for any help that you could give.

asked by: Michael R

Helpful Expert Reply:

Having a truck that old with tow package wiring for installing a brake controller is a new one on me, but I can certainly help you determine which wire serves what function.

Just about every brake controller out there will have four wires exiting the rear of it. The black wire carries 12-volts to the controller. Having a direct fused or circuit protected connection to the battery is the best way to provide this power. The white wire is the ground connection. Some will say that simply grounding this wire to metal under the dash is sufficient, but the controller manufacturers recommend connecting this directly to the negative post of the battery. The red wire is usually connected to the brake stoplight switch, or a dedicated stop lamp signal like a third brake lamp. The stoplight switch is usually used because its the closest place to get a signal. This circuit is what alerts the controller that the vehicle brakes are being applied. The blue wire carries the output voltage from the controller to the 7-way connector at the rear bumper.

You can confirm that the red wire you found is the 12-v feed to the controller by using a circuit tester like part # PTW2993 or a multimeter on it. This circuit should show a constant 12-volts. The red wire with green stripes can be tested also. This wire should only show current when the brake pedal is applied-not with the turn signals or running lights. The blue wire should be the output circuit to the 7-way. If that all checks out, connect the red wire you found under the dash to the black controller wire, the red and green striped wire to the red controller wire and the blue wire you found to the blue wire of the controller. Extend the white controller wire through the firewall to the negative battery terminal.

This all assumes that your truck has a functional 7-way trailer connector on the rear bumper.

expert reply by: Mike L