Brake light problem

Tiny
CLAY PITTS
  • MEMBER
  • 1987 MERCURY MARQUIS
  • 5.0L
  • V8
  • 2WD
  • AUTOMATIC
  • 97,878 MILES
Left signal will not flash when brake depressed. Operates normally otherwise. Noticed that when this happens center brake light goes out. Noticed that it will flash with pedal depressed without key being on but center light goes out also. Where to look for problem?
Friday, January 26th, 2018 AT 12:47 AM

8 Replies

Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
My be a bad ground connection. Check for moisture in the globe holder and corroded terminals at the light loom plugs. Start here.
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Friday, January 26th, 2018 AT 3:22 AM
Tiny
CLAY PITTS
  • MEMBER
  • 10 POSTS
Checked all lamps and wiring loom and all seems okay. No corrosion. All sockets have grease and all lights seem fine. Any other suggestions. All ground is tight and clean.I'm stumped
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Friday, January 26th, 2018 AT 10:34 PM
Tiny
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Do you have a trailer plug fitted? This is very symptomatic of a bad earth, make sure trailer plug concretions are ok if fitted, let me know if no trailer plug fitter.
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Friday, January 26th, 2018 AT 11:15 PM
Tiny
CLAY PITTS
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  • 10 POSTS
No trailer plug fitter.
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Saturday, January 27th, 2018 AT 3:38 PM
Tiny
CLAY PITTS
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  • 10 POSTS
Is it possible for the ground problem to be caused by the brake light switch on the pedal? I was feeling under the dash for that switch and I touched something that caused the lights to blink with the key off as I explained in my question.
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Saturday, January 27th, 2018 AT 8:28 PM
Tiny
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A faulty brake light switch will not turn on the brake lights. You can check that it is okay with a test light or a multi meter. Check for power through the switch with the pedal down. You should have battery voltage and nothing through the switch with the pedal up.
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Saturday, January 27th, 2018 AT 10:29 PM
Tiny
CLAY PITTS
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Checked switch and all is okay. Where are other places to check for ground other than the two wires grounded in trunk area? I am out of ideas on this problem and quotes from others to diagnosis and search this problem are outrageous. Any ideas?
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Monday, January 29th, 2018 AT 11:15 AM
Tiny
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You can try and splice into the earth and create a new earth solder a wire onto the earth and attach to a clean section of body see if this helps, if o it would be a safe assumption that the problem is an earth, also make sure that the globes are correct and the globe holder is not damaged in the base or the striker tabs that make contact with the globe.
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Tuesday, January 30th, 2018 AT 1:39 AM

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