2001 Ford F350 brake lights on permanently

Tiny
SKIDBOOT
  • MEMBER
  • 2001 FORD F-350
  • V8
  • 2WD
  • AUTOMATIC
  • 97,000 MILES
I noticed the brake lights ( both rears and upper cab lights) on when I shut the truck off after a short trip ( 4 miles) towing an 8,000lb trailer. The power light on my brake controller was also on. I disconnected the brake controller, no change. I removed the fuse for the brake lights, and they remained on. Everything works fine, including the brakes. I made sure the parking brake wasn't on. The only way to get the lights to go off is to disconnect the battery. Last brake job was about 30,000 miles ago. No problems since then
Saturday, October 31st, 2009 AT 12:46 PM

10 Replies

Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
Check the BOO(brake on off) switch on the pedal arm. Unplug it and test switch for proper continuity. An OHM meter will show OL when pedal is in released position, and zero ohms when pressed. If readings differ, replace the switch, if reasdings are OK inpect the wires to the switch.
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Saturday, October 31st, 2009 AT 12:58 PM
Tiny
SKIDBOOT
  • MEMBER
  • 6 POSTS
I disconnected and removed the BOO switch completely, and the lights are still on!
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Saturday, October 31st, 2009 AT 1:23 PM
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
Something tells me your trailer wiring needs to be looked at, you have a short to power to the brake lights. Look there.
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Saturday, October 31st, 2009 AT 1:26 PM
Tiny
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  • MEMBER
  • 6 POSTS
The trailer is not attached to the vehicle at this time
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Saturday, October 31st, 2009 AT 1:38 PM
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
Right, but it does have a connector for the trailer light? And it's wired into your lights? Right?
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Saturday, October 31st, 2009 AT 1:49 PM
Tiny
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  • MEMBER
  • 6 POSTS
That's correct
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Saturday, October 31st, 2009 AT 1:55 PM
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
These are the wires that most likey have the short, start there!
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Saturday, October 31st, 2009 AT 2:07 PM
Tiny
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  • MEMBER
  • 6 POSTS
I disconnected the trailer lights/brake connector from the main wiring loom under the bumper and the lights are still on. I can't see any evidence of any obvious problem with the wiring from where it comes out of the loom to the back of the plug for the trailer
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Saturday, October 31st, 2009 AT 2:21 PM
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
On the steering column find the connector for the multifunction switch(wiper and turn), and unplug it, tell me if the lights go out now, if so, replace multifuntion switch.
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Sunday, November 1st, 2009 AT 11:01 AM
Tiny
SKIDBOOT
  • MEMBER
  • 6 POSTS
Yesterday I needed to use the trailer, hooked it up, the lights were on, including the brake lights for the trailer. The trailer brake controller was disconnected. I drove 4 miles, got out and all the lights were out and everything works normally!
I use a "superchip" aftermarket unit which I always have set for " safe tow". Last week I had to have the truck emmissions tested, and had to return the truck to "stock" before going in there. It remained that way until yesterday, after the lights had gone out, pulling the trailer, I re-installed the super chip program. I don't believe that had anything to do with it at this point. I guess I can go no further until the problem re-appears. Thanks for your suggestions.
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Monday, November 2nd, 2009 AT 8:39 AM

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