No brake or third brake light.

Tiny
AUTOSTUDENT12
  • MEMBER
  • 1998 MERCURY MYSTIQUE
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 150,000 MILES
I've tried searching the Internet, now for hours. My friend is really down on her luck and came to me to try to help her. She has a 1998 mercury mystique automatic. She has no brake lights whatsoever. Turn signals work, taillights and hazards work perfect. I changed out the brake pedal switch but still no brake lights. Her spoiler is barely hanging on, ripped out by a friend who grabbed hold of it by accident so it is badly damaged, in fact, I didn't see any wires.
Wednesday, November 25th, 2015 AT 2:17 PM

7 Replies

Tiny
CARADIODOC
  • MECHANIC
  • 34,330 POSTS
Is the spoiler problem related to the brake light problem? Is there a center brake light in it? Have you checked for blown fuses? Did the brake light problem start at the same time the spoiler was damaged?
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Wednesday, November 25th, 2015 AT 2:54 PM
Tiny
AUTOSTUDENT12
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  • 4 POSTS
Yes, third brake light is in spoiler. I pulled the PDC fuses (all ok) but did not pull (roll) the fuse box down from under the dash. I did not want to break anything (i don't think it has even been pulled down). I thought since tails were working and 1 bulb controls brake lights and turns, that fuses were ok. Maybe not. I believe the spoiler was broken, and I think the brake lights were still working until recently. I am trying to clarify that now.
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Wednesday, November 25th, 2015 AT 3:07 PM
Tiny
CARADIODOC
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Is the center brake light on the car now? If it is, whether it works or not will provide a real fast indication of where to start looking. That circuit is real basic. The two rear brake lights go through the turn signal switch so troubleshooting them gets more involved.

Start by checking fuse 24, (blue 15 amp) in the fuse box on the left side of the dash. If that is good, check for 12 volts on the orange / white wire on the brake light switch. Next, check for 12 volts on the orange / yellow wire on the brake light switch when you press the brake pedal.

If you have the center brake light missing and / or you can access the wires, look for that orange / yellow wire and check for 12 volts on it when a helper presses the brake pedal. If that is there, the fuse, brake light switch, and wiring are all okay up to that point.
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+1
Wednesday, November 25th, 2015 AT 4:14 PM
Tiny
AUTOSTUDENT12
  • MEMBER
  • 4 POSTS
Thank you for working on this with me. Yes the center brake light is in the spoiler and is not working. Regarding the two rears, yes I was wondering if the MFS in the turn signal might be bad. I will have to delay responding answers regarding testing for 12 volts till I can get access to the car again.
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Wednesday, November 25th, 2015 AT 4:23 PM
Tiny
CARADIODOC
  • MECHANIC
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Dandy. Forget the signal switch for now unless we determine there's two different problems. The center high-mount brake light is fed directly from the brake light switch. It doesn't get its current through the signal switch.

Do the rest of the tests I suggested when you get the chance, then holler back with the results. I'm back here at least every other day.
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Wednesday, November 25th, 2015 AT 5:33 PM
Tiny
AUTOSTUDENT12
  • MEMBER
  • 4 POSTS
OK. Test light showed no power on either line at the back. Pulled down fuse box. Fuse was blown. Other fuses ok. Replaced with new fuse. Still no lights. Check brake light switch - no continuity. Put other BLS in. All brake lights functioning properly now. Drilled out rivets to gain access to spoiler bolts. Replaced 1 that was missing. Tightened both down. Friend was very happy. Thank you for all your tech support.
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Monday, November 30th, 2015 AT 7:13 AM
Tiny
CARADIODOC
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Dandy. Happy to hear you solved it.
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Monday, November 30th, 2015 AT 3:03 PM

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