Brake light troubleshooting

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Apr 17, 2012 | 10:04 AM

Mikulh

Thread Starter

Laughing Gas

Joined: Dec 2005

Posts: 904

Likes: 115

From: Laurel, MS

Brake light troubleshooting

On my '61 F-100 (non-uni) my tail lights and turn signals work on both sides, but my brake light only works on the LH side.

Looking at the wiring diagram it appears that the turn signal and brake light use the same wire and the same filament in the bulb... so I know the wiring and bulb are good since the turn signal works on that side.

This leads me to believe the problem must be in the turn signal switch. I have a friend who thinks it's the flasher unit, but I'm not sure how that could be.

What are your thoughts?

thanks,
Michael

Apr 17, 2012 | 08:33 PM

6t6merc

Cargo Master

Joined: Apr 2001

Posts: 2,697

Likes: 46

From: Vancouver

I think you got lucky. The wire goes from the cab to the left corner, then to the right , so the problem must be in the few feet from left brake light to right.
Eric

Apr 17, 2012 | 08:44 PM

jacks61ford

Senior User

Joined: Aug 2008

Posts: 484

Likes: 0

From: pahrump nv

If the turn signal on that side works and if the brake light feed on the left side is hot when the pedal is depressed you have a bad turn signal switch

Aug 7, 2012 | 08:50 PM

JoshDacres

Freshman User

Joined: Dec 2011

Posts: 29

Likes: 0

I'm trying to wire up lights for a flat bed, was hoping someone on this forum had a wiring diagram so I could find the right one. Right now I have a bundle of wires coming from the cab.... thanks for the help

Aug 8, 2012 | 05:10 AM

jowilker

Fleet Owner

Joined: Jun 1999

Posts: 24,552

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From: Creedmoor, North Carolina

Josh, Basically there are 3 wires going to the rear of the truck to run the lights. One to run the tails and one each to supply brake & turn signal (shared). Find those wires at the cab with a good circuit tester like this one, and getting them to the rear will be a piece o cake.

John

Aug 8, 2012 | 12:16 PM

SuperSabre

Laughing Gas

Joined: Dec 2010

Posts: 1,091

Likes: 14

From: Tucson, Arizona

For a stock wiring harness, your left tail light turn/stop filament wire should be yellow with a black trace. Your right tail light turn/stop filament wire should be green. Your tail running light filament wire (and license plate light power) should be brown. As jowilker said, use a circuit tester to be sure. Good luck!

Aug 8, 2012 | 07:59 PM

F250GH

Tuned

Joined: Aug 2008

Posts: 413

Likes: 2

I had the same problem. After tracing out the circuit with a tester as previously mentioned, I found the connection was bad on the firewall plug. Repaired the plug and all is good.