3rd brake light problem

R

redpr5

Member
:
2002 Protege5
i just got my protege back and now the 3rd stop light doesnt work at all.
the wierd thing is that no one has opened the hatch since its been at the shop.

i checked the plug for the light and it has power going in and out but the lights dont come on
the fuse is good and im guessing the relay is good as well (the other 2 lights work)
i have no idea whats wrong with them...any ideas?
i have my bumper lights disconnected because i like the way it looks without them lighting up but i dont think that would affect my brake light would it?
 
anybody got any ideas

i hooked the bumper lights back up and still nothing (didnt think it would make a difference)
 
bump before bed.
really need to figure this one out, i dont need any reason to get pulled over (i have tint that is WAAAAAAAYYYYY illegal in my state)
 
redpr5 said:
i just got my protege back and now the 3rd stop light doesnt work at all.
Click to expand...

Back from where? What were they doing to the car?

After you pull the plug (which you say had good voltage (at the place it goes into the 3rd light?)) try measuring the resistance across the input to the 3rd light. Be sure you have the polarity on the multimeter in the same direction as the normal voltage, as the unit may not be well protected against reversed polarity. If it's shorted or open that would indicate a problem in the light itself.

Clean the contacts too - couldn't hurt.

If all else fails try wiring 12V (assuming that's what you measured on the plug) directly to the unit, again, being very careful with the polarity. If it doesn't light up then most likely the unit is dead. I seem to recall reading that they could not easily be opened, so you'll either have to find a replacement or find some way to pry it open, fix it, and seal it up again.
 
pasadena_commut said:
Back from where? What were they doing to the car?

After you pull the plug (which you say had good voltage (at the place it goes into the 3rd light?)) try measuring the resistance across the input to the 3rd light. Be sure you have the polarity on the multimeter in the same direction as the normal voltage, as the unit may not be well protected against reversed polarity. If it's shorted or open that would indicate a problem in the light itself.

Clean the contacts too - couldn't hurt.

If all else fails try wiring 12V (assuming that's what you measured on the plug) directly to the unit, again, being very careful with the polarity. If it doesn't light up then most likely the unit is dead. I seem to recall reading that they could not easily be opened, so you'll either have to find a replacement or find some way to pry it open, fix it, and seal it up again.
Click to expand...

back from where i work (the garage). the light assembly is easy to take out, no clue about opening it though. i put a test light on both sides of the plug and it lit up on both sides, so i have power going in and out of the plug.
im hoping that the assebly isnt dead because iirc they arent cheap.
 
redpr5 said:
im hoping that the assebly isnt dead because iirc they arent cheap.
Click to expand...

But they should be - the active parts inside are dirt cheap and widely available. There appear to be some after market replacements around, not sure if any of these would fit a P5 though. See for instance:

http://www.commandelectronics.com/third-brake-lights.html

http://www.spoilerlights.com/servlet/StoreFront

Or if your car is really a Cylon in disguise:

http://www.youtube.com/watch?v=qtlcl-e_Pmc

If it were my P5 and this light was dead I'd probably dremel it open. Odds are whatever electronic bits that are broken in there could be easily repaired. If successful, then seal it up again with something like RTV sealant and put it back on the car.

After a bit of reading, it looks like some of these LED lights are epoxy filled. In that case you can forget about fixing it easily.
 
Last edited:
redpr5 said:
back from where i work (the garage). the light assembly is easy to take out, no clue about opening it though. i put a test light on both sides of the plug and it lit up on both sides, so i have power going in and out of the plug.
im hoping that the assebly isnt dead because iirc they arent cheap.
Click to expand...

You should be using a DMM or voltmeter to measure the voltage at the plug. A test light is not polarity sensitive, not can it tell you how much voltage is there. The third brake light uses LED's. And LED's are polarity sensitive. I would assume that it uses 12v to light, but it could be a lower voltage. I would measure the voltage at the plug, then find out what voltage is required to light the brake light. If the correct voltage is at the plug, then your assembly is probably bad.
 
5PADZAM said:
If the correct voltage is at the plug, then your assembly is probably bad.
Click to expand...

That's what I'm thinking.

There's also the possibility that a wire between the plug and the 3rd brake light unit broke. If that's the case then the resistance across the two leads on the lamp side of the plug, when it isn't plugged into the rest of the car, will be infinite. So it can be tested without having to remove the 3rd light from the car.

That said, you might as well take it off anyway. If it tests open, you have to remove it to find and repair the broken wire, and if it doesn't test open then there's probably something wrong with the circuit board inside the unit, and you'll still have to take it off to fix that or replace the unit.
 
i did use a voltmeter and it read 0.0v but the test light lit up.
im gonna have my eletrical guy tear down my spoiler friday and see whats up with it internally since he would know what to look for
 
Someone on the forum found this for the MSP 03.5 brake light but they have both stlyes if u just wanted to buy a whole new clear replacement. if not i have my old P5 rear wing with the brake light unfortunately i'm really not looking to seperate unless the price is worth it.. but check this out
http://www.spoilerlights.com/servlet/Detail?no=20#
 
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