No brake lights! Can't seem to find an answer..

[Team Dave]

Hopefully I can get some insight here, as I am a little confused. All I wanted to do was see if my 3rd brake light was still working, and I found out that none of them were! :woo-hoo:

I've done some research, and messed with a few things but haven't fixed it yet. All the searching I did couldn't help me either (you'd be surprised at the amount of "ATX/BOO Can't get out of park" threads there are!).

Here's my dilema. I'll try to cover anything I've done that may be related to it. I bought the car with a non-working 3rd brake light. I figured the LED's were dead, so I bought a new one on eBay, and it worked great. When I first bought the car, it's BOO was a bit melted towards the front (closer to the driver), but I solved this issue by taking off the top portion, and directly plugging the wires into the BOO (with those pancake lookin connectors. I have no idea what they are called). I checked to make sure it was all working right, and everything seemed fine.

Now, all of a sudden, I don't have any brake lights. I checked out the BOO, and all connections are solid, and it is getting constant power like it should. There was a black plastic piece poking out above the BOO that I had to re-insert into a white clip that pivots on the brake pedal, but I don't think this is related (I'm assuming it has something to do with cruise control?).

I've also checked the fuse (#1), and that was fine too... BUT there was a 20 amp there when it should be a 15 amp. I swapped it back to a 15, but I don't think that is what the problem is. It may have contributed to the partially melted BOO, but I don't see it negatively affecting anything else since it wasn't much larger of a fuse. And FWIW, my melted BOO is only cosmetic at this point. From what I can tell, the BOO is working completely fine. I'll probably replace it anyway, but I think my issue lies elsewhere.

That's it for the most part. I don't think theres any faulty wiring in the car, so I'm really trying to avoid having to trace it all to the fuse box. Anyone have any input on this?

 

[Mr Anonymous]

Aside from verifying voltage at the BOO, did you check its operation by probing the cold side of the switch for voltage with the brake pedal depressed?

 

[Team Dave]

Aside from verifying voltage at the BOO, did you check its operation by probing the cold side of the switch for voltage with the brake pedal depressed?

That I did not. Is that something that can be solved by replacing the BOO with a new one? Because for as cheap as they are, I might as well anyway. All other harnesses and wiring that I could see in the trunk were still intact. Nothing looked to be in bad shape at all.

I did re-wire in the 3rd brake light via the passenger side brake lamp harness, just to verify it was dead LED's. When I put in the new LED spoiler light, I used the factory harness and just capped off the two wires I put in. When this all happened, I immediately thought that was a probable culprit. I removed all the excess wiring and cleaned everything up, but to no avail. All the wires I had left were in fine shape, and my trunk doesn't leak any, so I don't think they were related..

 

[Mr Anonymous]

How did you verify voltage at the BOO? Presuming it was with a meter or test light, all you have to do is move the probe to the other leg on the switch and then press the brake pedal.

BOO switches are cheap and easy to fix, and they do fail so it's entirely possible. Another quick test would be to use a jumper to connect both leads going to the BOO switch and that alone should light up the stop lamps. If they light up then that just about guarantees a bad BOO.

 

[Grantorinslo]

Honestly I would just go ahead and doo the BOO. If you want I can bring over a test light/multimeter if you can't find yours, but I'm gonna be in SoCal until next friday.

 

[Team Dave]

How did you verify voltage at the BOO? Presuming it was with a meter or test light, all you have to do is move the probe to the other leg on the switch and then press the brake pedal.

BOO switches are cheap and easy to fix, and they do fail so it's entirely possible. Another quick test would be to use a jumper to connect both leads going to the BOO switch and that alone should light up the stop lamps. If they light up then that just about guarantees a bad BOO.

I did it with a test light. Good call with the jumper.. I'll go give that a shot right now.

Honestly I would just go ahead and doo the BOO. If you want I can bring over a test light/multimeter if you can't find yours, but I'm gonna be in SoCal until next friday.

Thanks, but I'll be getting this done tonight or tomorrow. Either way, hit me up when you're in town.

 

[Kens1992mtxSHO]

My money is on the Brake On Off switch. Cheap and easy fix.

 

[BlackonBlack89]

does the cruise control does turn off when u hit the brakes?

Yep my switch was fine but the wire got pulled out. So for a week or two I had no brake lights. Actually figured it out b/c the crusie control would fight the car even though I touched the brake. Scarred the crap out of me b/c Id hit the cltuch and brake at the same time and the car red lined it self

 

[Pro*banshee]

If those two don't work, the Red/Green wire is your brake hot wire. do the jumper trick as Mr Anonymous suggested, make sure you test at the multi-function switch too!!! My vote is for the BOO switch also, especially if the third eye isn't lighting. The third eye and the inside bulbs are on their own brake circuit as you can see below so there are really only so many things to actually screw up

I don't want to insert a massive image, but here's a (simplified) diagram of the wiring as laid out in the Chilton manual: http://www.thelegendofdanswall.com/wiring.jpg

 

[Team Dave]

Thanks for that picture! I'm replacing the BOO in a few minutes. I'll post my results.

 

[Team Dave]

Purchased a new BOO this morning, and just finished up the install, but unfortunately it doesn't look to have fixed anything. I wasn't able to check out back, but my test light wasn't getting a darn thing this time. Fuses are all still good. I'm going to mess with the BOO a bit more after lunch, because it was giving me a hard time during the install. Just to make sure everything is working fine down there.

I've seen some others mention underhood switches that may be a cause?

 

[SuperHO]

dangling down below your master cylinder (assuming an ATX) is a large connector. Probably about 8 wires across. unplug that. If I had an ATX out front, I'd go shoot a pic of it.

Apparently, brake fluid likes to leak on it and short out the connector. The only down side is that your cruise won't work and your horn'll be inop.

 

[Team Dave]

It's actually an MTX.. But my CC and horn aren't working regardless. I'm running an FR500 wheel, and they didn't want to work together.

 

[Team Dave]

Final update... they work now. I messed with the BOO some more, and they seem to be working correctly now.

I'm a bit confused at what my test light showed me though. When I was testing leads on the old BOO, I had my ground clip on the test light clipped onto the e-brake pedal.. when I touched the lower lead, I got nothing (as expected), but the upper got it to light up. I assumed this was right this as well.. Isn't the brake light circuit always hot?

After messing with the BOO a bit, the test light no longer lit up when I touched the upper lead. I swapped out the BOO for a new one this morning, and the test light still wouldn't light up for either lead.. I figured it didn't fix my issue because of this, but after going to look for myself, they all seem to be working fine now.

BUT putting that BOO on was a PITA. The open end wasn't wide enough to fit the old washer in. I was able to get it on finally, but it was fighting me the whole way. I couldn't even fit the outside washer back on. Don't think it'll be a huge deal though, I'll fix it later on down the road.