No clue how to wire the brake lights. Help 1971 F100

[sargentrs]

How much of this wiring do you have in place? Can you locate that wire along the driver's side frame rail?

[Ranchero50]

My issue is i can’t figure out which wires go to what.

You can buy a 12 volt test lamp at most auto parts places for a couple dollars. Strip each of the wires you have and connect each one into a light while the doing each of the following functions:

1. Park lights on, nothing else
2. Park lights off, left turn signal
3. Park lights off, right turn signal

As long as your front turn signal lamps are working you should get flashing voltage to the rear with the turn signals on.

Report what you come up with as you may have other problems upstream.

[BayStYAt]

How much of this wiring do you have in place? Can you locate that wire along the driver's side frame rail?

All I have in your picture is the 3 wire (brown, yellow, green) running down the right side of the from to the rear. I removed my bed to put the tank in and I scrapped all the junk wiring that was there. which was stupid because I can't get the wiring back to normal.

With a test light I was able to determine the parking and brake wires, I could not locate the revers lamp wires, or it don't get power to the (green wire)?

I hooked up the brown and yellow to the Driver side tail light. I hooked the green to the revers lamp. I was able to get the driver side parking and brake light to work correctly.

Then I just made a cross over wire to the passenger side and hooked it up the same way. Yellow and brown to the parking/tail light and green to the reverse.

well the driver side and passenger side parking worked, but when I pressed the brake the driver side would get brighter BUT the passenger side would go out completely. As if when I press the brake the passenger side light loses power.

I don't have side markers or lights for the license plate.


As for blinkers, I have nothing. Not even the flasher clicking under the dash.

[sargentrs]

This is going to be fun! You're going to have to travel further back upstream to a common connection. Take a look at this schematic. http://www.fordification.com/tech/image ... tem_HI.jpg Can you start working your way from the cab cowl back through the frame until you find a connector plug in that harness that lines up with the diagram? Or from the rear of the truck back up toward the cowl? You're trying to locate the 4 prong connector in the bottom center of this page http://www.fordification.com/tech/wirin ... ghts01.jpg (connector "J").

There are 4 wires that drive the lights to the rear of the truck:

282 - Green
283 - Yellow/Black
285 - Brown
140 - Black/Red

The 1157 bulb is a 2 filament bulb. The brown wire is the one that makes the lights come on when you pull out the knob on your headlight switch (tail lights, one filament). The green wire is what makes the driver's side turn signal flash via the TSS (2nd filament). The Yellow/Black wire is what makes the passenger side turn signal flash via the TSS (2nd filament). The black/red wire is what makes the tail lights brighter, via the brake light switch, when you step on the brakes (both filaments).

I believe the yellow wire you have is only for the side marker lights, forget it for now. You're missing the yellow/black wire. You need to find that connector "J" and start working to the rear from there. Follow the harness you have upstream and see if you can locate it.

[basketcase0302]

If I were a betting man I'd say your issue lies in the infamous TSS.
It's one of the only places the wires can short from one side to the other like that.
But this is AFTER you've verified a good ground to the circuits back there like Randy suggested.
Save yourself a lot...of problems and run a dedicated ground from your negative batter post, (I always ran a #12 copper stranded wire on mine) all the way back to the rear light assemblies.

[BayStYAt]

This is going to be fun! You're going to have to travel further back upstream to a common connection. Take a look at this schematic. http://www.fordification.com/tech/image ... tem_HI.jpg Can you start working your way from the cab cowl back through the frame until you find a connector plug in that harness that lines up with the diagram? Or from the rear of the truck back up toward the cowl? You're trying to locate the 4 prong connector in the bottom center of this page http://www.fordification.com/tech/wirin ... ghts01.jpg (connector "J").

There are 4 wires that drive the lights to the rear of the truck:

282 - Green
283 - Yellow/Black
285 - Brown
140 - Black/Red

The 1157 bulb is a 2 filament bulb. The brown wire is the one that makes the lights come on when you pull out the knob on your headlight switch (tail lights, one filament). The green wire is what makes the driver's side turn signal flash via the TSS (2nd filament). The Yellow/Black wire is what makes the passenger side turn signal flash via the TSS (2nd filament). The black/red wire is what makes the tail lights brighter, via the brake light switch, when you step on the brakes (both filaments).

I believe the yellow wire you have is only for the side marker lights, forget it for now. You're missing the yellow/black wire. You need to find that connector "J" and start working to the rear from there. Follow the harness you have upstream and see if you can locate it.

you guys are awesome. Ok so I see the J plug under the hood on the inner fender. Just from a quick look I can see when the PO replaced the original wires that run to the rear with this 3 wire run. My next step is to unglug the J plug remove the electrical tape and see why he only has 3 wires running to the rear and not 4. I will report back

[BayStYAt]

OK great news. I unplugged the J plug and tested with a light that the blinkers, parking and brake light all had power to the j plug.

Now at the plug the blinkers only stayed lit. They did not blink and the test light build was very dimly lit.

[sargentrs]

That would be an issue with your flasher. Have you replaced it? Now all you need is wire and crimp/solder.

[BayStYAt]

That would be an issue with your flasher. Have you replaced it? Now all you need is wire and crimp/solder.

Never replaced the flasher. thanks again gents!

[sargentrs]

Replace the flasher first. Cheap n easy to do and eliminates a variable. Do you have an emergency flasher switch in your glove box or is it somewhere else? The flasher works from the turn signal switch, the emergency flasher switch and the brake light switch. First check your turn signals by manually operating them off and on while checking the green and yellow/black wire at connector "J". Check if your test light goes on and off as you operate the blinkers. That will give you a clue if the problem is in the TSS switch or the flasher.

Backup lights are operated differently depending on your tranny/shifter option. What do you have?

[BayStYAt]

Replace the flasher first. Cheap n easy to do and eliminates a variable. Do you have an emergency flasher switch in your glove box or is it somewhere else? The flasher works from the turn signal switch, the emergency flasher switch and the brake light switch. First check your turn signals by manually operating them off and on while checking the green and yellow/black wire at connector "J". Check if your test light goes on and off as you operate the blinkers. That will give you a clue if the problem is in the TSS switch or the flasher.

Backup lights are operated differently depending on your tranny/shifter option. What do you have?

Ok so there is a flasher for emergency and one for blinkers? I found the round one for the blinkers under dash. I

[sargentrs]

Not sure. '70 diagrams only show 1. '72 diagram shows 2, 1 close to the TSS and 1 close to the emergency flasher switch. I believe the turn signal one is behind/under the instrument cluster and the E-flasher one is around/under the glove box. If you have the E-flasher switch in the glove box, trace the wire to find the flasher.

[BayStYAt]

Not sure. '70 diagrams only show 1. '72 diagram shows 2, 1 close to the TSS and 1 close to the emergency flasher switch. I believe the turn signal one is behind/under the instrument cluster and the E-flasher one is around/under the glove box. If you have the E-flasher switch in the glove box, trace the wire to find the flasher.

awesome. will look in the am

thank again

[BayStYAt]

Not sure. '70 diagrams only show 1. '72 diagram shows 2, 1 close to the TSS and 1 close to the emergency flasher switch. I believe the turn signal one is behind/under the instrument cluster and the E-flasher one is around/under the glove box. If you have the E-flasher switch in the glove box, trace the wire to find the flasher.

help with plug identification under hood driver side on top inner fender

in the first pic the plug on the top is the rear tail lights. the middle plug has 2 purple wires.

[sargentrs]

Take a look at this photo. http://www.fordification.com/images/fai ... 9518hi.jpg. It's high resolution so you can zoom in. Is this similar to the colors and wires you're seeing? I'm thinking that last pic is the brake warning light.