RyanFlemington

well, I posted this on bcrotary, but I think it's time to hit the "big" site. Here's my problem.

Righto, so I left my daylights on last night while I was at work, and by the time I got back, my car was dead. I went to get it boosted, and I got some power; my dashlights would turn on but not my headlights or my interior lights. On closer inspections today, and after changing my battery and terminals, I noticed that the black 80a main fuse was blown. So i jumped around the corner to mazda, picked one up, and went back to the parkinglot where my car is. I disconnected the batt and tore apart the fusebox to get the old fuse out and the new one in. As soon as I reconnected my battery, the new fuse blew, and now I'm stumped as to what would have caused this. I havn't changed anything with my car. The only aftermarket accessory is an alpine deck that's been in the car for some time now. Maybe something was wrong with my procedure? I'm really not sure, so any help here is greatly apreciated.

scrip7

iTrader: (6)

It would be helpful to know if you fully charged the battery before starting it up or did you just jump it and start it? The alternator's rectifier or voltage regulator may be fried, just one possibility. What a lot of people don't understand about alternators is that they are not designed to bring an almost dead battery up to a full charge. They are only designed to maintain a full charge and proper system voltage to run the car once it's started. They will tolerate a few "jump starts" but if you'll notice, the alternator gets very hot very quickly after a jump start. If your alternator was borderline before this happened, it might be shorted from heat buildup. Here's what to check first (if you have volt/ ohm meter)....Disconnect the battery ground cable. Remove your 80 amp main fuse. Turn all accessories off, doors closed, etc. Connect one meter lead to chassis ground and the other to one of the lugs of the fuse box where you removed the fuse. On one of the lugs you should see infinite ohms (zero) and the other you will probably see your short (probably less than 10 ohms) With your meter still connected, remove the batt wire from your alternator's post and unplug the other connector of the alt. If your meter reading shows no more short, replace the alternator. If you don't have a volt/ ohm meter (dvom), you can buy a couple extra fuses, charge your battery completely, disconnect the alternator and see if the fuse blows when you connect it. If it still blows with the alt disconnected, then do the dvom test while removing the other fuses one at a time that share the 80 amp circuit. The FSM should show what's on the circuit. Good luck.