need wiring gurus in again.
01-08-2009, 01:09 PM
#1
need wiring gurus in again. so i was outside looking at my tail lights and have now noticed that the 3rd brake light is on (very dim) all the time and it is bothering the S*** out of me. i checked and for some reason all my brake lights are getting 6-9 volts when the key is turned on and the brakes are not pressed. all the tail lights get normal 12-14 voltage when i press the brake pedal but i cant figure out why they are getting low voltage instead of none when the pedal isnt pressed. and its only when the key is turned when it isnt they are fine. anyone have this happen to them? im not sure what to check all the fuses are fine and the only thing ive done lately is led tail lights and i didnt change anything but wire the tail lights. both the positive lead to the brakes lights and positive lead to the 3rd brake light get voltage when they shouldnt.
-andy
-andy
01-09-2009, 07:40 AM
#2
If ALL of your brake lights are getting volts, then the first thing I'd check is the pedal switch.
If you remove the lower IP panel above your pedals, you'll see a switch mounted above the brake pedal with a plunger that is activated when you press the pedal. If you disconnect that switch and your brake lights get 0 volts, then that should be the source of your problem.
If the switch is it, then it may just need adjustment. If I recall correctly, you can rotate the switch in the mounting bracket to back the switch off the pedal to calibrate when its actuated. (it could be contacting just barely enough now to leak come current) If adjusting doesn't work, then you'd need a new switch.
If you remove the lower IP panel above your pedals, you'll see a switch mounted above the brake pedal with a plunger that is activated when you press the pedal. If you disconnect that switch and your brake lights get 0 volts, then that should be the source of your problem.
If the switch is it, then it may just need adjustment. If I recall correctly, you can rotate the switch in the mounting bracket to back the switch off the pedal to calibrate when its actuated. (it could be contacting just barely enough now to leak come current) If adjusting doesn't work, then you'd need a new switch.
01-09-2009, 01:15 PM
#4
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i had the same thing...did you use diodes with your tail lights? you are probably geting feedback in the system.
I used Zener diodes to eliminate the issue.
I used Zener diodes to eliminate the issue.
Last edited by fast01z28; 01-09-2009 at 01:23 PM.
01-10-2009, 09:54 AM
#6
A diode http://en.wikipedia.org/wiki/Diode limits the direction electricity can travel in a circuit.
If your brake switch isn't the issue, then you may just have a short. Have you done any work in your dashboard lately?
If your brake switch isn't the issue, then you may just have a short. Have you done any work in your dashboard lately?
01-10-2009, 09:59 AM
#7
A diode http://en.wikipedia.org/wiki/Diode limits the direction electricity can travel in a circuit.
If your brake switch isn't the issue, then you may just have a short. Have you done any work in your dashboard lately?
If your brake switch isn't the issue, then you may just have a short. Have you done any work in your dashboard lately?
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01-10-2009, 10:25 AM
#8
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Originally Posted by italicizedsponge
i didnt change anything but wire the tail lights. both the positive lead to the brakes lights and positive lead to the 3rd brake light get voltage when they shouldnt.
01-11-2009, 12:43 PM
#10
Oooooh. I missed the point about your LED project.
When you do things like this, (changing the resistance in the circuit) you need to remember that you have changed the physics and behavior of everything on the chain - including the brake pedal switch!
Fortunately, this is a simple circuit. You just have the fuse, the switch, and the lights involved.
I'd suggest doing the following:
- With the car and all of your accessories off, use a voltmeter to measure the current across your brake light fuse. If the voltage across it matches what you are seeing at the tail lights, it will confirm that you have an issue contained to that circuit and that the problem is not due to a short circuit with another source.
- If the above is good, you should test the brake pedal switch and see what happens. (Disconnect the switch and then check the voltages.) If the switch was adjusted right "at the edge" to begin with, the changes in the circuit may be inducing some arching in the switch, which may be a source of the leakage. If that is the case, you may be able to adjust the switch to resolve the problem.
When you do things like this, (changing the resistance in the circuit) you need to remember that you have changed the physics and behavior of everything on the chain - including the brake pedal switch!
Fortunately, this is a simple circuit. You just have the fuse, the switch, and the lights involved.
I'd suggest doing the following:
- With the car and all of your accessories off, use a voltmeter to measure the current across your brake light fuse. If the voltage across it matches what you are seeing at the tail lights, it will confirm that you have an issue contained to that circuit and that the problem is not due to a short circuit with another source.
- If the above is good, you should test the brake pedal switch and see what happens. (Disconnect the switch and then check the voltages.) If the switch was adjusted right "at the edge" to begin with, the changes in the circuit may be inducing some arching in the switch, which may be a source of the leakage. If that is the case, you may be able to adjust the switch to resolve the problem.
01-12-2009, 11:14 PM
#11
from what people here have said and my buddies at work said that since i did led tail lights it is causing the feedback in the system. i am going to try what others have said and wire a diode on each brake light wire and see what happens. the switch is good i have tested that