third brake light problem..believe me i searched
#1
third brake light problem..believe me i searched
I have read everything this site and any other site has to offer on the 3rd LED brake light on a 993.
The light does not work. Wires on outside of glass get 13V. wires on inside get 13.5V. Light by itself hooked up to a 12V battery works fine all LEDs light right up. Fuse 19 for stoplight and cruise control checks out fine. Replaced it just in case still same issue. Am i missing something? Thanks in advance for your help.
The car is very low miles 15K and is a 1995. Got to pass inspection and it wont unless i get the silly light to work.
The light does not work. Wires on outside of glass get 13V. wires on inside get 13.5V. Light by itself hooked up to a 12V battery works fine all LEDs light right up. Fuse 19 for stoplight and cruise control checks out fine. Replaced it just in case still same issue. Am i missing something? Thanks in advance for your help.
The car is very low miles 15K and is a 1995. Got to pass inspection and it wont unless i get the silly light to work.
#2
Rennlist Member
Your car has to have a functioning 3rd brake light to pass inspection? What State? Half the cars I see around here don't have working lights. Is it a case of if its there it has to be operational? Why not remove it for inspection (I assume your car doesn't have the basket handle)?
Not sure why its not working since the system appears fully functional the way you describe.
Not sure why its not working since the system appears fully functional the way you describe.
#3
Nordschleife Master
Brandon,
just to be clear, you should get 0v outside until the brake pedal is pushed. when the brake pedal is depressed, you should THEN get 10+V.
assuming that is true, and the lights work when you apply direct battery power, the only thing that can be wrong is a bad connection between the lights and the car.
stranded wire CAN become brittle, and connectors can become loose. try wiggling the wires and twisting the connectors to see if you can narrow it down.
just to be clear, you should get 0v outside until the brake pedal is pushed. when the brake pedal is depressed, you should THEN get 10+V.
assuming that is true, and the lights work when you apply direct battery power, the only thing that can be wrong is a bad connection between the lights and the car.
stranded wire CAN become brittle, and connectors can become loose. try wiggling the wires and twisting the connectors to see if you can narrow it down.
#4
im in north carolina so the third light has to be there on anything 95 and newer.
i tested the wiring with the brake pedal pressed. i tried wiggling the connectors twisting them even roughed them up with a scotch brite with no success.
last resort i may just hard wire the darn thing or at least replace the barrel/bullet style connectors.
The car is a turbo so it has the third light located at the top of the rear glass.
i tested the wiring with the brake pedal pressed. i tried wiggling the connectors twisting them even roughed them up with a scotch brite with no success.
last resort i may just hard wire the darn thing or at least replace the barrel/bullet style connectors.
The car is a turbo so it has the third light located at the top of the rear glass.
#5
Nordschleife Master
Hopefully that never happens.
#6
Rennlist Member
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#8
Three Wheelin'
So, it seems that the power is there when you test it without the light in but it does not get to the light when it is reinstalled -- and that the light works when out of the car. So, logic would seem to say there is a short in the wires to the light or in the light itself when connected. Try this: Remove the light, test the power. If hot, re-connect the electircal connections to the light without reinstalling the light and test. Does it work? The probably the problem is with the wires when light is installed. Also, how are you testing the light itself? In other words, try to isolate where the short is.....
#9
Nordschleife Master
So, it seems that the power is there when you test it without the light in but it does not get to the light when it is reinstalled -- and that the light works when out of the car. So, logic would seem to say there is a short in the wires to the light or in the light itself when connected. Try this: Remove the light, test the power. If hot, re-connect the electircal connections to the light without reinstalling the light and test. Does it work? The probably the problem is with the wires when light is installed. Also, how are you testing the light itself? In other words, try to isolate where the short is.....
I am guessing the connectors are bad and "open" thus not powering the light[s].
if there were a short, a fuse should be blowing somewhere.
#10
Burning Brakes
Brandon - if your car has the center brake light upgrade to LED's then it is as simple as swapping the leads. The LED's need the correct polarity to work otherwise they are off.
If they are the original incandescent bulbs then swapping the leads is not going to solve it.
If they are the original incandescent bulbs then swapping the leads is not going to solve it.
#11
I had a similar problem with my 3rd brake light. Turns out it was the ground. Run a jumper from the ground terminal on the lamp to a good grounding location. I used a bolt in the drivers door jamb. I then did the pcar.com fix on thee ground wire at the top of the rear window. Once i got in there, it turns out The power wire had already been done.
Good luck
Good luck
#12
Instructor
Are you talking about leds ?
If it is so you know for sure that + and - must connect to the right input wire, and when reverse the PN junction of the leds work as open circuit...
I guess you already know that and check it but I think it's worth the try...
If it is so you know for sure that + and - must connect to the right input wire, and when reverse the PN junction of the leds work as open circuit...
I guess you already know that and check it but I think it's worth the try...