Brake lights stay on

Tiny
JIMMYSIDEKICK
  • MEMBER
  • 1996 FORD MUSTANG
  • 4.6L
  • V8
  • 2WD
  • MANUAL
  • 84,000 MILES
Replaced brake light switch and connector and checked the fuses. Brake lights still stay on until I pull the "boo" fuse or disconnect battery. What is my next step?
Thursday, July 5th, 2018 AT 5:13 PM

5 Replies

Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,004 POSTS
I just looked the diagram over.

Then I screenshot it and added notes.

Looks like the brake pedal switch is the only thing that could turn them off or on.

To verify this, Do they go off if you unplug the switch?

If so, it's the switch or the mechanics of the pedal linkages keeping the switch activated.

This type of switch is a pain and sometimes tricky to install.

As the pedal is pushed in there is kind of a cam action happening that "makes" the switch (turns the switch on).

If there is/ was a plastic/ rubber bushing for the switches hole, insure it is not missing, cut or badly worn.

I found a video for a Ford that might aid you in rechecking your installation.

https://www.youtube.com/watch?v=WXOtWVSaL-E

Diagram I got from "Prodemand" is below.

Let us know what you find!

The Medic

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Thursday, July 5th, 2018 AT 7:22 PM
Tiny
JIMMYSIDEKICK
  • MEMBER
  • 4 POSTS
Unplugged the connector from the switch and the lights stay on. Everything on the switch seems to be good.
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Thursday, July 5th, 2018 AT 7:28 PM
Tiny
JIMMYSIDEKICK
  • MEMBER
  • 4 POSTS
Could it have anything to do with the multi-function switch on the steering column?
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Thursday, July 5th, 2018 AT 7:51 PM
Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,004 POSTS
You may be right!

I made two more closer up screenshots.

I traced out fuse 9 with yellow (if you trace out fuse 1, make the switches move, it could do the same thing).

I think you can rule out the flasher because the hazards in the multi-function switch have to be switched over in order to power the brake lights.

Play with the hazard switch to see if you have any change.

Pulling out fuses 1 and 9 one at a time might narrow down which part of the multi-function is stuck/broke/etc.

The only other possibility I can come up with is a hot wire shorted to a brake wire in a wire bundle.

Most likely a new multifunction switch may be the ticket.

Pictures below (follow the fuse 1 possibility that I did not trace out).

The Medic
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Thursday, July 5th, 2018 AT 8:24 PM
Tiny
JIMMYSIDEKICK
  • MEMBER
  • 4 POSTS
Thanks so much for the help. I will keep trying to figure it out.
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Thursday, July 5th, 2018 AT 8:33 PM

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