So this weekend I noticed my subs were cutting out when the car was turned on, so when I got home I started poking around looking for loose wires, etc. When I opened the hood I heard a bubbling noise coming out of the battery, I took the battery out and realized it was bulging out on the sides and foaming/leaking. So I let it sit until it stopped making noise and then drove to the parts store to get a new one. At this point my SRS light came on, but I didn't have time to look into it.

As I pulled into the parts store the top of the battery blew off and battery acid got all over everything. I got a new battery and had them test the charging system, sure enough, the alternator was running at 17V, and it was overcharging the battery. So I got a new one and put it on and had them test it again, the new alternator is fine. The problem is, being a dummy I didn't disconnect the battery until halfway through the install, and I arced off something in the engine compartment. (The ground wire for the alternator got ahold of something else)

Anyway, fast forward to tonight, the first time I've driver in the dark since Saturday, I go to back out of my driveway and I have no reverse lights, also no brake lights. I have tail lights, the brake lights just aren't working. I checked the fuse under the hood that says "Back up" and I checked the back up lights fuse under the dash and both are fine. I'm at a loss, electrical problems are the bane of my existence. Any help would be appreciated.

tl:dr battery blew up due to bad alternator, botched the install, now SRS light is on and I have no reverse lights or brake lights.

 

I jumped the wires off at the brake switch with no result, I'm guessing that this means there's a short somewhere between the fuse box under the hood and the brake switch. So I guess I just follow it back from there? I'm gonna get a test light after class today and see what I can figure out.

 

Have you checked the bulbs? Overvoltage is murder on bulbs. Every single one may be blown. (Whenever something doesn't light up on a car, ALWAYS check the bulb first, and THEN if it's not that, investigate further.)

If you short out the big wire on the alternator by trying to R&R it without disconnecting the battery first, that will usually blow the big alternator fuse in the underhood box. Which on most models renders the whole car dead but on some it may just prevent charging.

The brake lights and the horn are on the same fuse (under hood). I think the turn signals and reverse lights are on the same fuse (under dash).

The "BACK UP" fuse under the hood is for "backing up" the memory in the ECU and the radio, it doesn't have anything to do with lights.