Well after a couple years of procrastinating I finally cracked open the 3rd brakelight and tested all the components... You can get the part(s) at Radio Shack for just a few bucks.


Note: this repair is for when all 6 LED's are dim or completely outt. If some LED's still work this isn't going to help.



Here's the culprit -- 1N4007 diode which is way small for these LEDs. The diode looks fine... but it has become an open circuit because it overheats:








You should replace it with a single 1N5404 -- it is bigger (3Amp instead of 1Amp). I already had two 1N4004 in my toolbox (leftover from alarm installing days) so I used them and doubled them up for more current. You can get these at Radio Shack. Notice the orientation of the stripe... it won't work if you install them backwards:






And there we go





Hopefully this saves you guys some $$...people were trying to sell me used ones for $150+

 

Edit: mods feel free to move this thread to the DIY section if need be.

 

Wow on the sedan its a 1N4007

So going down to 1n4005 would still work and be more reliable?

 

Actually I was wrong (updated post) on both the actual diode part number and the recommended replacement...my old man eyes are failing me

you'd actually want something like a 1N5404 which will handle 3x the current. All of the 1N400n diodes are only 1A. Even though the actual current is only 0.3 they get really hot... The last number really isn't important, it's just the reverse voltage rating and there is no reverse voltage here because the LED are not inductive.

 

Pays to know a thing or two huh?

Well played

 

The BSEE paid off...finally!

 

Aw yeeee EE that's how you do it hahah.

Glad you posted this. Dealerships charge like $450 or somthing to have it replaced haha

 

We do make replacment boards . Only problem with this DIY is that when they fail changing the diode wont fix the problem on 90% of them . Diode should be changed but that wont fix burnt out LEDs or loose connections or sometimes there are other problems as well .

 

^^ Interesting. I haven't seen enough to know the most common failure mode... but if you have all the LED's out (or all leds lit very dimly) this fix will work. It's rare for an LED to fail, even more rare if every single LED failed. If an LED went closed circuit (again, very rare) you'd most likely see a burnt resistor.

Either way it's a cheap DIY so what is there to lose.

 

Is this DIY of high difficulty, Im a complete electrical newb. I dont have any electrical knowledge or equipment. Can i just get the diode and is it an easy swap? thanks in advance.

 

can someone post a link with a DIY on how to remove the 3rd brake light on coupes?

 

you can literally just pull it up and towards the front of the car, at least that's how mine came out.

 

Bought a G35 third breaklight was out. Simple fix of changing the diode. My local place didn't have an 1N5404 But 1n5408 worked just fine. a couple of the LED were not working but a simple re solder of the connections fixed that too. Fix cost me 2 hours and $5.00.

 

Thank you so much for this informative post! My third brake light will sometimes work and other times not. I am assuming this will fix the problem. I have not actually soldered anything electrical before, only plumbing. I have a soldering iron though, so my question is what size of solder would you recommend for this job and how much wattage will be needed? What else would I need? Flux and maybe a soldering wick?

Thanks, Jeff

 

I am not the best at soldering and found this to be beyond my ability. Impossible IMO to soldier without removing the circuit board from the assembly which is braced into place and also is retained by both the + and - contacts which are also soldered. maybe if I had two more hands I could do it..... but soldering from the top of the board with the larger 1N5404 is a very difficult task. Just a warning to the people without soldering experience. Wasted 2+ hours and a trip to radio shack before giving up. I hope it works for everyone else!