Brake lights always on

Tiny
KZEPPY1
  • MEMBER
  • 2011 CADILLAC ESCALADE
  • 6.2L
  • V8
  • 4WD
  • AUTOMATIC
  • 120,000 MILES
Recently my brake lights will not shut off with the key on. I have replaced the brake switch with a new OEM switch. I started removing fuses to see what was powering the lights. When I remove the LT stop trn, RT stop trn fuses the respective side brake light shuts off and just the running lights stay on, however the brake lights will not work when pedal is depressed. Not sure if It is potentially a shorted wire or possibly bad control module?
Thursday, September 24th, 2020 AT 5:23 PM

3 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,179 POSTS
Hi,

Do the brake lights (both) turn off when you disconnect the brake light switch? If not, then the issue is likely near the body control module. See pic 1.

Disconnect the switch and let me know if the lights go off. If it does, check for a short between the purple wire and the orange/white wire at the switch. (See pic 2) One is a 12v reference wire (when the key is on) and the other is a signal voltage. If the purple wire has 12v without actuating the switch, that is the problem.

Let me know if you have questions or what you find.

Take care,
Joe
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Thursday, September 24th, 2020 AT 6:03 PM
Tiny
KZEPPY1
  • MEMBER
  • 3 POSTS
The brake lights do not shut off when the switch is unplugged.
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Thursday, September 24th, 2020 AT 6:15 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,179 POSTS
Hi,

Okay, I need you to confirm if power exist on the body control module where the two wires attach from the switch. See pic.

Let me know if there is constant power, power with only the key on, or no power at all.

Also, let me know if the high-mount brake light is also turning on and if the problem started all at once. There are logic modules that may be an issue, but both wouldn't have gone bad at the same time.

Joe
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Thursday, September 24th, 2020 AT 7:08 PM

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