'50 Brake light issue

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Jan 2, 2014 | 10:06 PM

saxtonj

Thread Starter

Mountain Pass

Joined: Aug 2000

Posts: 139

Likes: 1

From: Marshall TX

'50 Brake light issue

I just upgraded my truck to 12volt. No wiring changes were made as I used the reproduction 6volt that I bought several years ago. I replaced all wiring from headlights to taillights. I replaced all 6volt bulbs with 12v. Now every time I push brake pedal there is no brake lights and when I push brake with headlights on the headlights dim a bit and the dash lights go out and the brake/tail lights go out but have a faint flicker.

What the heck happened?

Jan 2, 2014 | 10:10 PM

imabaka

Senior User

Joined: Jul 2009

Posts: 289

Likes: 0

From: North Platte NE

To me it sounds like a bad ground issue. I'd make sure that there is a good ground to the taillights. Bad grounds can cause all sorts of weird issues.

Jan 2, 2014 | 10:34 PM

Rimrock F1

Posting Guru

Joined: Apr 2013

Posts: 1,170

Likes: 2

From: Rimrock AZ

The two things I would look at firs are grounds (if things act weird it is usually a ground problem). If they are OK I would check for shorts in the Brake power supply wire. When you changed from 6V to 12V did you change from positive to negative ground?

Jan 2, 2014 | 10:40 PM

saxtonj

Thread Starter

Mountain Pass

Joined: Aug 2000

Posts: 139

Likes: 1

From: Marshall TX

Yes... I did change from pos to neg ground.

I've had the truck on the road for 13yrs and have put probably 5-6 brake light "switches" in the truck. They seem to fail regularly for some reason.

Jan 2, 2014 | 11:54 PM

ALBUQ F-1

Fleet Owner

Joined: Jul 2004

Posts: 27,294

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From: NM

Buy one at a Ford dealer.

Jan 3, 2014 | 02:56 AM

NumberDummy

Ford Parts Specialist

Joined: Nov 2006

Posts: 88,826

Likes: 785

From: Simi Valley, CA

Brake lamp switch is pressure activated, it's notorious for getting gummed up with dirty brake fluid.

C1AZ-13480-A (replaced 0A-13480) .. Brake Lamp Switch (Motorcraft SW-24).

1940/66 myriad FoMoCo vehicles.