Well, I tried everything I could figure to do. I have the wiring diagram( maybe not reading it right?), have juice at the brake pedal switch, all other functions work in the tal light assembly, but no brake lights. Checked underneath with a test light and have some of the wires showing current. I hate wiring ,please help.

 

Bad bulbs? Bad sockets? Wiggle the bulbs around and make sure they are making the connection.

 

No power to one side of the socket, lights up the test light on the tail light side, but no juice for brake lights

 

You say all other functions are working. Is the turn signals working if they are working I would check the brake light switch or it also runs through the turn signal switch. If there not working I would check the grounds because the tail light ground can back feed though the brake light, usually the lights aren't as bright when this happens.

 

I have tail lights ( lights that operate when headlights are turned on) turn signals and backup lights. I have hot at the brake light switch and at the other side when the pedal is depressed. I have been using this diagram http://automotivewiringdiagrams.net/...ng-diagram.jpg but am not familiar with the device between M and N. If I am correct in reading this, the brake light is powered by 383 red/white stripe to 284 red out to the brake light switch. 810 red w/ black stripe is the wire that comes off from the brake light switch when closed and goes into a connector. I can follow the wire to the switch, but it goes into a taped harness from the brake light switch and I lose track. Any body been to this point and can give me a little direction?

 

There are 3 wires going to the rear of the truck down the drivers side frame rail. 1 wire is for tail lights, the other 2 are for brake and shared with turn signals.

If you have turn signals (both sides) then the brake lights should work as they share the same wire.

Have you done any recent work to the wiring at the front of the truck? The steering wheel area?

You are sure with the ign. switch on and the pedal depressed there is power on the second wire at the brake light switch (power out).

Something is stopping brake light power. And if the turn signals are indeed blinking on the rear, it's at the front of the truck.



John

 

Ughh, bunch of spaghetti. Do you know the location of the components circled in red? wiring diagram by gearhed1971 | Ford-Trucks.com

 

There looks to be a branch off the main group of wires midway back around the back of the cab , these have been cut off by the p.o.,but the group of wires that is supposed to go to the rear does . I hate wiring

 

What you have circled is the turn signal switch, right under the steering wheel. The wire that leaves the brake light switch runs through the trun signal switch that is way I ask if they worked. If power is going through the brake light switch and the turn signals are working it has to be the turn signal switch or the wire between it and the brake switch

 

Ok, my turn signals operate with the key off, is that normal for this year?

 

Key has to be on for mine to work

 

Sounds like someone's done a fine bit of muckery on the wiring. Turn signals should only work with the key on, so it's getting power from somewhere. If there isn't a wire obviously installed outside of the harness or something grafted in, then likely the switch is shorted internally.

 

Even if the switch was internally shorted, how would that cause it to be under power with the key off?

 

2x Ford_Six in post 12.

 

I was thinking the wrong direction. Brake light power comes from the pedal switch, up to the turn signal, I was thinking the other way.
Sounds like somebody messed with it pretty well.