Break Light Blues

[brynndragon]

The two main break lights of my car are being non-functional (the only working one is the one in the rear window). I want to see if I can solve this problem without taking it to a shop.


My first thought was to check the fuses and make sure it isn't tripped, since both going at once seems more likely to be an electrical issue of some sort. However the shop manual lead me to believe that they're located underneath the panel just below the steering column, so I've yet to actually look (I didn't have the proper tools to do so when yulecat noticed the problem, but Xmas has changed that ;). After talking extensively with dragonvpm about it, my plan of attack is as follows: 1) check the fuses and replace if necessary. If that doesn't work (or the fuses are unbroken), 2) replace the bulbs. If it still doesn't work, 3) replace the break switch. That last one would be the trickiest overall, but this is a case where being a relatively small person is useful, since it involves squeezing into the footwell on the driver's side (actually, so does 1, but what I recall of the picture says that the fuse box is much easier to play with). However, I'm a dumbass who left all her shop manuals at home. I probably can't even ponder 3 while I'm down here (as in I won't know what part to get until I can consult the manuals, much less get it ordered), but 1 and 2 should be doable. If I do all three and it still doesn't work, I'd guess it was a short somewhere. I don't know if I could even attempt to find a short, much less fix it. So here's hoping one of the above fixes the issue. . .

Comments

[qedrakmar.livejournal.com]

Go buy yourself the Haynes Manual for your car model. Following the wiring diagram in the back, use a multimeter and test for continuity with the break pedal depressed. If there's a short it should be obvious by changes in voltage.

[benndragon.livejournal.com]

I've got both the Haynes and the Chiltons, but they're back in MA. Getting my hands on a multimeter would be the more difficult part; I might have to go out and buy one. Yea, this is why it's good to have clueful folks as friends :).

[metahacker.livejournal.com]

I have a multimeter, and my standing offer to help you do this still, uh, stands.

[benndragon.livejournal.com]

Yay! Assuming the bulb thing doesn't pan out, we can play with the multimeter. I'm glad I'm fairly small, as the place with the wires is a bit of a squeeze even for me.

[bikergeek.livejournal.com]

If the one in the rear window works, then the problem is neither the fuse nor the switch. If the problem were the fuse or the switch, the center brake light would be non-functional along with the ones on the corners. My guess is that both taillights are burned out. Bad luck? Coincidence? Were you riding around with one light non-functional for a long time?

[benndragon.livejournal.com]

It's possible that rather than redesign the wiring from scratch they just added stuff on later for that light, which could mean a seperate fuse (unlikely, but possible). There's also the possibility of a short after the place where they split off. However, as dragonvpm pointed out, cars don't always function via logic - when the motor that controls the electrionics in one of the doors of his car failed, the power locks still worked but the power windows didn't. But yea, bulbs before break switch. Far as I know both lights were working fine until recently. . .

[dragonvpm.livejournal.com]

Actually I may have explained that poorly, when the motor that powered the passenger side window started to give out, the driver side switch would no longer activate it, but the passenger side switch would. At a glance this would seem to indicate that either the switch or the wiring to the motor had failed, but in fact it was the motor.

Not all vehicle components fail completely, while I looked around for stuff last night, I noticed that several times people complained that their brake lights were starting to fail, but hadn't yet stopped working and in those cases it was still the switch. The consensus seemed to be that if bulbs, and fuses were intact and there were no major wiring issues to be deal with, then it was the switch since those tend to start failing in some way after 100k-120k miles.

It's possible, for instance, that the switch is simply not providing enough power to light all three lights and is only lighting the smaller third brake light as a result.

[benndragon.livejournal.com]

I checked the fuse and it's fine (although it's a bitch to get to the fuse box because the fucking morons who installed the aftermarket alarm put it on top of said fuse box; I was extremely close to ripping that damn thing out altogether). So next check the bulbs, then check via multimeter for a short, then get a new switch (which is actually fairly obvious, based on the pics you showed me yesterday).