Battery Draining/Blown fuse

[240240]

Ok guys, heres the problem....my battery keeps draining, I cant find anything that is draining it, but get this the other day I was charging the battery and one of my main fuses blew (If you look under the hood at the 240 fuse box, second column, top fuse (75 amp). I bought a new fuse $18!! and put it in, blew right away. Anyone ever experience a problem like this, could this be the cause of my battery draining or just coincedence?

[mmatl16]

your alternator is prob going out

[240240]

Thats what I thought about my battery, but that wouldnt cause the fuse to blow would it?

[Wulfgang]

Which fuse? What does that fuse do (what does the fuse box cover say)?

[240240]

Fuse doesnt say anything, if you look at the fuse box under the hood, it is the second column from the passsenger side, top fuse (75Amp fusable link)I have no radio, lights, no fuel pump, fans

NOTHING =(

[240240]

I bought a New one, put it in and it blew right away

[240240]

Top of Fuse Box (under Hood)

Column 1 Column 2 Column 3 75A FL

[rb250sx]

Its a master fuse, it connects directly to the altenator and the fuse box. If your altenator isnt grounded well it will blow that fuse. Once that fuse blows nothing in the car will work. I had this problem when i first wired up my car, and i had a bad ground connection to my altenator.

[240240]

ill check it out

[240240]

I cant see where the alternator grounds---do you remember right off?

[sean8564]

It

I cant see where the alternator grounds---do you remember right off?

it should be a nut on the back of the Alternator.

[USMCgetsome]

small screw on back of alternator and if you need a good chasis ground use the grounding point where all the other wiring on the block is grounded by the water temp sensor. If that still doesn't do it for you then check your power wires, seems like you have a 12vdc wire grounding in the system.

[Wulfgang]

Then that's a fusible link, not a fuse. And at 75A, your battery would not be just "draining." It should be lighting something up, starting a fire, that kind of thing. Only a few wires in the car can carry that kind of amperage without melting.

So. What exactly were you doing when the fuse blew? Did you have the battery in the car (hooked up) as you charged it? And what about the second time it blew?

[Slo_240sx]

Get a circuit breaker from your local parts store so youre not blowing 18 dollars fuses all day long. If you suspect a grounded alternator disconnect the battery then everything on the alternator without grounding the output wire on a ground somewhere. Then connect the battery back up if it pops then its not your alternator. If it still pops it may be some alt wiring grounded. Take your test light and see if you have power going to your output wire to your alternator. Its the one with the 10MM nut. that goes back to the battery from the alternator known as the "alternator output wire". That should have a constant power from the battery. If you do not have power there with the circuit breaker closed and output wire disconnected from the battery than you have an open wire.

Another thing to try to pinpoint a parasitic is to pull fuses one by one. Disconnect your battery and put 1 end of the test light on the battery post itself and the other on the battery cable. The light should light dimm for about 5 seconds. That is KAM (keep alive Memory) for your clock, ECU, etc... when the key is off. The light will go off after 10 seconds or so. If not you have a short. MAKE SURE DOORS ARE CLOSED! Your interior lights may kick on the test light! If the test light is lit you have a draw. Pull Fuses 1 by 1 and when the light goes out thats where your draw is. Look up a wiring diagram and inspect wiring on that circuit or any components on that circuit. Hope i didnt confuse you but diagnosis can be tedious.

Also, Look over ignition switch wires... Like if you put in a turbo timer, alarm, remote starter... They tend to blow the Master fuse if you've been in there and not taping or splicing wires correctly. Check wiring to your alternator and any other main components like the starter and such. It must be a big draw/short to blow the master fuse. Try that and get back with us.

-Alex

[240240]

I found the short, it was in my turbo timer. I dont understand why it would just start shorting out though? Anyways, I took it off and everything is good..

Thaanks everyone for your help

[BoostFab]

good job!

be sure to always solder and tape/heat shrink your connections, just the best way to avoid shortage and failure points.