Why a blown battery fuse??

[vlaar]

The other night we had quite an electrical storm outside. Didn't think much of it the next morning when I went outside to start my car. Car starts and runs fine, but there is NO radio or power door locks. Kinda strange. So I pop the hood and check the fuses and BAM, blown battery fuse. I probably should have known this but I blew another battery fuse while I was replacing the bad one. I still had the battery connected when I was attempting to put the new battery (40A) fuse in. This time around, I disconnected the neg. terminal, installed the new 40A fuse and bam, radio and locks are back What exactly is the battery fuse for though, besides making the radio "work" etc?? Also, I heard some spark noises coming from the alternator area when I was hooking the battery terminal back up. I'm hoping I didn't do anything. I always see the sparks usually around the battery terminal if I'm hooking it back up but never the alternator. Keep your fingers crossed! Thanks.

Kevin

 

[its3much]

well i do know that if there lot of electrical current in the air it will blow your fuses. it happened 2 me when some guy hit a transformer an knocked power out for like 3 city blocks an my fuses blew

 

[vlaar]

Damn this car Battery fuse is blown AGAIN! I don't even no where to start now. Someone please help? I don't want to have to sell the car because of a "minor" issue like this one. But I can't afford to keep going through this time and time again. Car runs fine, I just have no radio and no power door locks. Thanks.

Kevin

 

[Mike1992]

Most likely your arcing somewhere, you said you seen spark on the alternator, look at the main power wire that connects to the stud on the alternator, make sure theres that rubber/plastic washer behind it and that its not arcing on anything, that'd be my guess. Done any ghettofied wiring jobs lately? Install the stereo yourself, when?

 

[vlaar]

No weird radio wiring that I know of. The weird thing is I put in a new battery fuse yesterday. And then today, I drove to school with the radio working and all. I come out of class and BAM, no radio or power door locks. Please help. I'm really hoping I don't break down on teh interstate tomorrow when I'm driving 4 hrs south to go home... Battery voltage still reads 13+ volts according to the logger, which is good. This is nonsense and I'm not sure if I can keep dealing with these little problems (laughs--here comes a Toyota Camry)!! Thanks.

Kevin

 

[1LE]

So, all that "breaks" when the fuse blows is the radio and power door locks? You *always* see sparks when connecting the battery?

Do you still see sparks when connecting the battery when this fuse is blown?

Perhaps you have a wire that has rubbed through on a sharp edge in the car. Perhaps part of the radio wiring harness is rubbing on some of the sharp metal of the center console supports? Of course, with the power door locks failing as well, perhaps you have a short in the power door lock wiring (it runs near some sharp edges on the inside of the door)?

If those are the ONLY things broken when the fuse is blown (make sure that turn signals, brake lights, etc DO work), I would leave a blown fuse in there for the long drive and only try to fix it before a short drive. Don't risk further damage by replacing the fuse without examining the wiring first. There may be a lot of wires in these cars, but it's really fairly easy to get "visible access" to the majority of the problem areas. Just takes a little time and patience.

Oddly enough, I had a VERY similar problem with my MR2. It turned out that the wiring inside the fog light when twisted a certain way would just barely rub and short. Wiring actually looked fine (no visible cuts), but it was touching a sharp edge. Re-routing (and taping the wiring up too, just for good measure) solved the problem.

Oh yes, best advice anyone ever gave me... Make sure to use Scotch electrical tape, costs more, but trust me, it's the BEST thing around. Super 33+ is the thinner stuff (and most likely what you will need) and easiest to work with, 88+ if you need thicker tape (like for big honkin' wiring).

 

[vlaar]

Brake lights, turn signals, dash lights all work. No, I don't always see sparks when I reconnect the battery. Yeah, I'm not touching anything since the car runs fine as is. Keep the suggestions coming. I'll have plenty of time the rest of the summer to work on it since I'm done with coursework here at UF One step at a time! Thanks guys.

Kevin

 

[tsigrl2016G]

First off, this is a lot to read, i just wanted to give you all the info, so if you scroll down to all the ****'s, that's the jest of the answer
what had happened to my car was that the fog light wires were shorting out because they were wearing in a way that they rubbed and the ground wire was touching the power. Well, there was a thirty amp fuze in for the fog lights when it only called for a 15 amp, so, naturally, when the fuze tried to blow because of the short, it couldn't, and the wires got so hot, it followed the entire engine wiring harness, and melted and burnt wires together. I've been saudering and splicing and taping the wires up and getting the harness all clean again,,,the car still ran during all of this.
But i had some fuzes in the multi-purpose junction box still blowing, like my horn wouldn't stop beeping, and my key reminder switch won't shut up, they're on seperate fuses though. The horn is because one of the melted wires was touching the wire for the horn, where it connected to the dedicated fuze box under the hood. But, there was another fuze that kept blowing in the junction box under the steering wheel. It was #19 multi-purpose fuze, yours is a '90, so your electrical circuits are set up the same as mine. That #19 fuse controls and completes circuits for the radio, pwr door locks, mpi control unit (that's right under your ecu, attached actually), mines an automatic so that fuse was also for the auto transaxle, and i have abs brakes, so, it also completed that circuit, and dome lights. For the '90 though, you had a choice of either abs brakes, or limited slip rear differential for those cars,,do you have abs brakes?
Anyway, i didn't have my stereo, or door locks, because that fuse kept blowing. Well, we went through every circuit that was connected to that fuse and at last when we left the abs unit unplugged and turned on the car, it didn't blow. Everything on that fuse had a battery source, that's why we couldn't figure out why it blew only when i turned the car on. But the abs unit was the only thing that tapped into that fuse, but had an ignition source. I don't want to buy an abs unit right now, so, we just left the relay for the unit unplugged....it's either a bad unit, or one of the two wires that it feeds is bad, which i found yesterday is actually melted.
**** But, yeah, the radio and the door locks work off of #19 fuse in the junction box under the steering wheel,,,,has that fuse ever blown? If not, it's nothing to do with the wires that run from the battery to that junction box; it's the wires that run from the battery to the battery fuse. There's a short in them somewhere. Radio keeps going out because the radio's circuit has the battery as the power source (that's how you can turn the stereo on without turning the car on), and if the battery fuse keeps blowing, it's keeping the current from continuing on to feed the radio circuit. Test the wires from the batt. fuse to the batt. to see the amps running through them, a short will be caused by too much current. Either that or simply replace those wires. If it was your alternator, it would've blown the alternator fuse. Check the output of your alternator just to make sure it's charging the battery the way it should. It's not your radio, if that 19 fuse hasn't been blowing. If those wires from the batt. to the batt. fuse test fine, or you replace them, and the same thing happens,i'd look at the alternator/connections next. Oh, and test the batt. volts too. Let me know what you find and i'll try and help from there.
kylei

 

[TurBoGs-T]

I had the exact same problem and i went thru like 2 or 3 fuses. Hopefully it will just go away just like mine did. But i had the no radio and windows either. Good luck

 

[tsigrl2016G]

i tried to hope my problem would go away by itself, but i guess my little dsm thought that would be too easy, and next thing i know, right driver side fenders off, mass air/filters out, fans are out, coolant overflow can's out, inside dasch is out, and i'm knee deep in fixing wires... all while the car's still drivable. Love those dsm's! so many things can go wrong with them and yet they still run.. Oh, and all this while the power steering pump was leaking on the alt. so, replaced alt. a few times and stupid autozone batt was leaking acid.

 

[vlaar]

Thanks everyone. I just did a head swap on my car with my mechanic, so I haven't had time to look into this electrical issue. Hopefully, it'll be simple. Anyway, I always see people having problems with the power steering fluid leaking onto the alternator. Is there a cover that anyone has built to prevent the alternator from being leaked on?? Just curious. Thanks.

Kevin