2004 f150 supercrew brake switch bypass

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Printed Date: July 21, 2025 at 1:24 AM

Topic: 2004 f150 supercrew brake switch bypass

Posted By: crustysarge
Subject: 2004 f150 supercrew brake switch bypass
Date Posted: December 30, 2007 at 2:11 PM

I have a 2004 F150 Supercrew 4X4 that I have to prepare for European market registration. This entails installing yellow bulbs in the revers lights and converting them to turn signals. A separate white light will be mounted under the rear bumper for a reverse light. Also have to do some headlight mods and drill/install turn signal indicators in the front fenders just below the 150 emblem.

Now here is my problem. Since the red turn and brake lights are tied together I have to bypass that circuit by cutting the output side of the brake switch and running a new wire directly to the rear for the brakes. Other splices in the back are made to rig up the signals and new reverse light. Unfortunately the 4X4 switch is tied through the brake switch circuit for 4X4 low insertion. I need to locate this circuit and tie the 12v signal from the brake switch to it AFTER the turn signal circuit. Make sense? Since the original brake circuit routes through the turn signals I have to connect after since I am disconnecting the factory brake circuit to prevent them from blinking.

Anybody have a diagram to see where I can make the splice and save me some time?

Replies:

Posted By: Ween
Date Posted: January 01, 2008 at 8:59 PM

hi,

can't you just eliminate/ cut the input wire to the turn signal/ hazard switch....light green? then use that wire (not the switch side) as the feed for your brake lamps. the switch contacts of the brake switch for the brake lights do not interface with the 4x4 switch. a different set of contacts is used for that circuitry.

mark

Posted By: 1sicgsr
Date Posted: January 03, 2008 at 3:48 PM

why dont you just cut the turn signal wire at the bulb socket and splice in a piece of wire between the power and ground, and leave the brake lights alone?

Posted By: 1sicgsr
Date Posted: January 03, 2008 at 3:51 PM

sorry, i wasnt clear there, basically, you are taking the turn signal out of the brake bulb socket, and moving it to the reverse light socket. you can do the same thing for the reverse light, just cut the wire at the socket or in the harness, and run a new piece of wire to the under side of the bumper. use a new ground.

Posted By: crustysarge
Date Posted: January 04, 2008 at 1:53 AM

The wire for thje turn signal and brake are the same. 3 wires at the socket, ground, tail pos, turn/brake pos. This is why you must run a new wire for the brakes. I do this frequently on cars for export.

Yes the 4x4 switch is connected to the brake circuit. There are two sets of contacts on the brake pedal. One is for the cruise control shutt off and has two wires. The other has 4 wires, two control the park interlock circuit and the other two (light green) control the brake turn signal. If the brake pedal is not pressed the truck will not switch to 4x4 LOW.

Anyway, after tracing the circuit I have not been able to find the 4x4 tie point. There are two light green wires that go into the steering column that are hot when brake is pressed. I cut them both and that works. Turn works and all other circuits function. It appears the 4x4 tie point is before that.

Posted By: Ween
Date Posted: January 04, 2008 at 4:33 AM

hi again,

is the F150 the new or old body style? i have schematics for both vehicles.

you remove the tail lights housings, find the hot wire (light GREEN/ orange and ORANGE / light blue) for the turnsignals/brake lamps on each side and cut them. next you find the wires for the reverse lamps(BLACK/ pink?) and cut them. you take the vehicle side of the turn sig/brake wire connect to reverse lamps(respective sides of course). add new reverse lamps...connect to old reverse wire. run wire from turn sig/brake lamps forward to cab of vehicle. find output lead of brake switch (light green) and connect to brake lamp wire. cut brake switch input wire at turn sig/hazard switch (light green).

if it is the newer F150, there are two light greens at the turn sig/hazard switch (cut both)

brake lamps light when brake pressed, turn signals/hazards operate bulbs in reverse lamps housing, reverse selection operates new under bumper lamp.

mark

Posted By: crustysarge
Date Posted: January 04, 2008 at 2:42 PM

Ween, thanks for the reply but already done! It is the new style and you are correct on cutting the two lt green wires.