I have an '02 F150 with the factory towing package. I bought it used and am installing a brake controller, and a 7 pin plug, it came with a factory 4 wire. I have had the controller since '01 or so, so it's not a new one, but has the standard blue, red, white and black wires. My main question is the factory controller plug under the dash. It has 5 wires, along with the blue it has a red and a light green one. These two are hot when the pedal is depressed, and the blue one is not. Which wire should I use the red, or the green, to go to the controllers red wire, or does it make a difference? I have not found where the blue wire comes out at the rear, or does it? Thanks

 

'02 Ford
Factory wiring brake controller harness:
Blue - Brake control feed to trailer
White- Ground
Brown- Illumination (not needed)
Red- Positive power feed
Green- Switched brake source

You will need to wire White to white
Black on controller to red on harness
Red on controller to green on harness
Blue to blue
Don't use the brown on the harness.

 

I wired up from the factory plug like you said, but I am getting low voltage from the blue wire out of the controller. The meter says a little over 2 volts with gain up all the way, but when I work the slide I get 11 volts. The red and the green from the factory harness have good voltage. This acts like a bad ground, but when operated by hand it works corrrectly. Any ideas? Thanks for the help.

 

If the hand operation works, it is working correctly.
You probably have a propotional controller with a pendulum.
As you hit your brakes the pendulum swings increasing the braking voltage only while braking or by pressing the manual brake control to apply the maximum braking.

What brake controller do you have?

 

I have a Hayes Energize III. I got on their website, and it said if the white wire is not grounded good then the red light will be dim, and bright when manually worked. I grounded the white wire to the dash, and still only get 2.29 volts, but 12.70 when manually worked. You may be right, it may be impossible to get a higher voltage reading when sitting still, and not moving. It does have the pendulum, and worked fine when I removed it from another truck 6 or so years ago. I may give them a call and see if a higher reading is possible. Thanks

 

There is a leveling arrow (grey lever on left side) that should have been set when you installed the controller. This sets the level for the pendulum. You can manually adjust level and your voltage should change to confirm the pendulum is working.
Just remember to set it back to level when you are done.