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

[BayStYAt]

The only wires I have that run to the rear of the truck are Brown, green and yellow. (original) wires. I am unsure how to connect these to the tail lights. The wire is on the driver side.

with trial and error I was able to wire the driverside and get the parking light and brake light to work. I figured hell easy, I will just extend the same thing to the passenger side. Well no, I got both parking lights to work but when I press the brake the passenger side goes out and driver side works correctly.

I know I don't have much information but hopefully with some hep I can diagnose this and get it working. \

thanks in advance

[The Bandit]

https://www.fordification.com/tech/schematics_i.htm

May be something here that can help you out.

[tsherry]

Try here.
http://fordification.com/tech/schematics_h.htm

If you're still having issues with tail and brake lights, check your turn signal switch. Problems there can show up in the back of the truck.

[BayStYAt]

thanks for the help, but I need a wiring brake lights for dummies.

[Ranchero50]

Should be similar to trailer lights if memory serves. Brown is dim marker elements, yellow and green are bright brake / turn signal elements.

[sargentrs]

Here's the diagram for a '72 which should be fine for your rear wiring too. The colors are the same http://www.fordification.com/tech/wirin ... _quick.jpg. Focus on the right side of the page which is your rear harness. Start by removing the tail light chrome and lens and pull the housing out of the body. Take some fine grit sandpaper, steel wool or Emery cloth and clean out the bulb sockets, clean the mating surface on the back of the housing, and try to clean out the screw holes. If you see any ground wires screwed inside the housing or body, remove the screw, clean the mating surfaces and reinstall. Do this at every screw, housing, ground wire and bulb socket then put it all back together except for the lens and bezel. When you have the grounds clean, then we can start troubleshooting for real. Poor grounds are the most frequent issues with wiring flakiness. Put the bulbs in and see what works and what doesn't. Check the full length of your rear harness from bulb to bulb against the wiring diagram looking for breaks, cuts. burnt places, etc. Then grab a voltmeter and we can start checking power sources and connections.

[BayStYAt]

Here's the diagram for a '72 which should be fine for your rear wiring too. The colors are the same http://www.fordification.com/tech/wirin ... _quick.jpg. Focus on the right side of the page which is your rear harness. Start by removing the tail light chrome and lens and pull the housing out of the body. Take some fine grit sandpaper, steel wool or Emery cloth and clean out the bulb sockets, clean the mating surface on the back of the housing, and try to clean out the screw holes. If you see any ground wires screwed inside the housing or body, remove the screw, clean the mating surfaces and reinstall. Do this at every screw, housing, ground wire and bulb socket then put it all back together except for the lens and bezel. When you have the grounds clean, then we can start troubleshooting for real. Poor grounds are the most frequent issues with wiring flakiness. Put the bulbs in and see what works and what doesn't. Check the full length of your rear harness from bulb to bulb against the wiring diagram looking for breaks, cuts. burnt places, etc. Then grab a voltmeter and we can start checking power sources and connections.

Awesome thanks. unfortunately I only have the Brown, yellow, and green wire coming from the cab. I currently have nothing hooked up. I need to basically create my own new harness to run to both tail lights.

this is all I have to start from.

[BayStYAt]

seems like this is my only option

https://www.npdlink.com/product/wire-as ... 7824/50696

[basketcase0302]

"BayStYAt"seems like this is my only option

https://www.npdlink.com/product/wire-as ... 7824/50696

NPD is describing that as a "crossover" (which I'm sure just runs from one side to the other? I'd call them before ordering it.

Those are the only three wires that run back there, (the lights get their ground from the chassis).
Brown= both parking lights.
Yellow=left turn and brake light , (gets the brake light "signal" from the TSS).
Green=right " " " ", (" " " " " " " ).

[BayStYAt]

"BayStYAt"seems like this is my only option

https://www.npdlink.com/product/wire-as ... 7824/50696

NPD is describing that as a "crossover" (which I'm sure just runs from one side to the other? I'd call them before ordering it.

Those are the only three wires that run back there, (the lights get their ground from the chassis).
Brown= both parking lights.
Yellow=left turn and brake light , (gets the brake light "signal" from the TSS).
Green=right " " " ", (" " " " " " " ).

ok, so let me ask you this question. I was able to get the driverside to work (parking/brake). but the passenger side would go out when I hit the brake. any reason why? meaning the passangerside parking light and drivers would work. When I hit the brake the driver side would work correctly but the passenger side would lose power on go out.

[sargentrs]

Check and clean the grounding points. Bad grounds can create multiple gremlins, including the symtoms you're describing. Not saying that definitely is the problem but it's a simple thing to do, doesn't cost anything and eliminates a variable. Also swap/jumper the left lights and the right lights and see if the problem changes sides. That will narrow down if the problem is on only one side or further upstream.

[sargentrs]

Still need to check the grounds but on reviewing the diagram, the only thing in common between the brake light switch and tail light bulbs is the hazard light flasher and switch. Have you replaced that flasher and is the switch operable? What's happening with the front parking lights while all this going on? Just checking all the variables.

[BayStYAt]

Still need to check the grounds but on reviewing the diagram, the only thing in common between the brake light switch and tail light bulbs is the hazard light flasher and switch. Have you replaced that flasher and is the switch operable? What's happening with the front parking lights while all this going on? Just checking all the variables.

Currently I have no lights hooked up up front. I have the front grille and all light off the truck. The turn signals worked before i pulled all the light off. I tried the blinkers and I don’t here the flasher clicking.

So currently i am trying to get the rear brake lights working with no parking or headlights connected up front. Could this be the issue with the rear?

[sargentrs]

Nah. Every light will work indeoendently and all plugged in to various connectors near their lights. I'm still leaning toward bad grounds on the side tthat doesn't work or a break in the harness.

[BayStYAt]

Nah. Every light will work indeoendently and all plugged in to various connectors near their lights. I'm still leaning toward bad grounds on the side tthat doesn't work or a break in the harness.

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