Brake lights stay on

ROOKIESTANG

MEMBER
2010 FORD MUSTANG
3.7L
V6
2WD
AUTOMATIC
200,000 MILES

Recently my car when turned off had the brake lights stay on.
-I did change the brake light switch and still stayed on
-I disconnected the switch it still stayed on.
-I pulled fuse 2(Good fuse) "BOO" and they go off, played with the hazard lights and they blink with fuse 2 removed and messing with my multi-switch to see if after plugging fuse 2 back in to see if it works (still on).
-With fuse 2 plugged in (lights still on) and pressing on hazard lights switch the lights blink but the upper middle brake light still on.
-Once in a while when I removed the car battery connectors and have fuse 2 removed and put them back in it works like normal for a short time until I drive the car.
-I've been scratching my head for a bit and trying to follow these wires: Looking at all the switches that control the brake lights from my car locking/opening mechanism, brake light switch, hazard light switch, flashers, light switch when driving at night, I did not check them all since I did not want to mess anything more up.

Side note: When driving around my Trac Off light comes on at random and sometimes I can't turn it off, not sure if that is relevant or not, because it is right next to the hazard light button and the trunk button.

6 Replies

ROOKIESTANG

MEMBER
4 POSTS

-Also did pull back on the brake pedal, still, brake lights are on.
-When the car works after having fuse and car battery removed and reconnected.
1. Brake light switch works, just saying.

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Thursday, August 1st, 2019 AT 8:14 PM

SCGRANTURISMO

MECHANIC
4,897 POSTS

Hello,

This could be an internal short to power in your vehicle's Body Control Module B (BCM)(B) which is located in the right rear of the luggage compartment. It is after fuse #2, so unplugging the fuse would cause a break in the circuit as you can see in the wiring diagram of your vehicle's external lighting. I have included in the diagrams down below for you as well as a diagram of the BCU B's location. Please go through these guides and get back to us with what you are able to find out.

Thanks,
Alex
2Carpros

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Friday, August 2nd, 2019 AT 4:28 AM

ROOKIESTANG

MEMBER
4 POSTS

Followed the diagrams, after looking everything over and driving for a bit after going to the car wash. I noticed the lights come back on and the Trac Off light come on once in a while. I noticed my Cowl had water sloshing around and built up, the water went into the Cabin filter, and moistening the passenger side floor next to fuse box, would this be the internal short? I have some pictures and not sure if I found the culprit to the brake lights staying on and the trac light coming on once in a while. If this is the problem will electrician wd-40 work on fixing this and new electrical tape for the wiring since most of it is unraveling on its own and covered in a oily substance? Or will this have to be taken care of by a ford service location?

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Sunday, August 4th, 2019 AT 7:51 PM

ROOKIESTANG

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4 POSTS

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Sunday, August 4th, 2019 AT 7:52 PM

SCGRANTURISMO

MECHANIC
4,897 POSTS

Hello again,

If it isn't the problem, then it soon will be. Okay, the electrical connectors can be cleaned up yourself. CRC makes a special cleaner for electrical connectors and it should be available at any auto parts store. It is called QD electronic cleaner and again, it is manufactured by CRC. That should clean up the corrosion the is producing the unwanted resistance on these circuits. Next you should probably get a tube of Dielectric Grease and put on these connectors. It is conductive grease that will help to weatherproof them. Finally, you need to fix the original problem, which is the water collecting and getting into the cabin. Wherever it is getting in at needs to repaired, or else this will happen all over again. Please keep us informed as to how things progress.

Thanks,
Alex
2CarPros