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Old 12-27-2012, 02:12 PM   #1 (permalink)
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Default Stoplight Switch

Still trying to sort out problems with my sequential tail lights. When I push on the brake pedal the right brake light comes on but the left doesn't. Could this be a problem with the switch, or does it lie elsewhere. I always thought a brakelight switch either worked or didn't... not work for one side but not the other. Any thoughts or experiences are appreciated.
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Old 12-27-2012, 02:21 PM   #2 (permalink)
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The brake light switch on the brake pedal is "on" or "off". That single switch controls both brake lights. So if one side works, but the other side doesn't, it isn't the brake light switch.

Could it be a bad ground connection on the side that doesn't work?
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Old 12-27-2012, 02:40 PM   #3 (permalink)
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The brake light switch feeds through the turn signal switch before the power gets to the brake lights. If you have the left or right turn signal on, the turn signal switch disconnects that rear light from the brake light circuit so that the rear light will still blink when you have the brake pedal depressed. If it wasn't done this way, with the turn signal on the rear light would blink when you weren't pressing the brake pedal and then would go solid when you pressed the brake pedal (if you have ever noticed, the emergency flashers do this - they blink when on and then go solid when you press the brake pedal - this is normal for the way they are wired).

What you describe could certainly happen if you have a bad turn signal switch. A bad ground can also cause the same thing and is usually the culprit. The taillight and turn signal lamp should share the same ground. Turn on the headlights and see if your taillights come on. If they still don't come on, you probably have a bad ground. If the taillight comes on but the blinker doesn't work, the ground is probably okay and the problem is in the turn signal switch or the wiring connecting everything together.
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Old 12-27-2012, 02:41 PM   #4 (permalink)
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Per chance, is your turn signal switch moved to the side that is out? That's what happens when the key is off. After the power makes its way through the brake light switch, it runs up the column and through the turn signal switch, then back down and out to the lamps. It's quite possible that somewhere between the turn signal switch and the lamp housing itself you have a bad connection or possibly a bad ground at the lamp. The turn signal switch could also be buggered.
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Old 12-27-2012, 03:02 PM   #5 (permalink)
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Thanks for the suggestions. The way it is now everything works but the left brake light. Tail lights work and sequential turn signals work. The brake lights are also sequential in that, starting with the inside bulb, they go inside, middle, then outside once then stay on until the foot is removed from the brake. Since I know the brake filiment of the bulb is brighter I am wondering if one of the three bulb filaments burns out will it prevent the other two from working. Will replace all 3 tonite and find out. I did just have a new steering wheel installed, and at the time replaced the cam so the turnsignals would cancel. I wonder if the mechanic somehow caused the problem.
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Old 12-28-2012, 07:58 AM   #6 (permalink)
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If you replaced the whole turn signal switch and not just the cam, you could check the harness plug by the steering column. I had one wires pin connector not making contact.
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Old 12-28-2012, 09:49 AM   #7 (permalink)
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Did you check for volts at the taillight? If it is a ground issue, you will get volts there, but the faulty ground will prevent the bulbs from lighting up. Have someone press the brake pedal (or put something heavy like a big book on it) and then check for voltage at the connection in the trunk. No volts = something under the dash isn't working.

Also, If you don't register voltage on the bad side, be sure to do the same test on the side that works. This will ensure the voltmeter is connected properly and is working. i.e. - you get a good reading on one side, and the same test on the other side comes up blank, then you know you aren't getting volts to that side.
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Old 12-28-2012, 11:22 AM   #8 (permalink)
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Hi Guys. Thanks for all the suggestions. Everyone who mentioned the turn signal switch as the culprit... give yourself 1 point. That's where the problem is. By gently rocking the turn signal arm up or down I can control which brake light comes on. Don't know if theres some kind of adjustment in there, or somehow something got messed up when the new cam was installed. Anyway, now that I know where the problem is I can fix it. Hope everyone has a healthy and happy 2013!
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