Lennyseleven

I bought a 90 GT the other day and Im trying to figure out whether it needs a battery or an alternator. I had the battery charged and tested and supposedly it is good, I brought it home, put it in and it started right up and the batt gauge stayed right in the middle. So today, two days later It wont start or anything, everything is dead. I jump it and it starts right up, but the gauge is at the low end of normal and goes down whenever you run the windows up or down, etc. There are no drains on it that I know of.

thanks
Nick

TheGmKiller331

Well theres a few ways to check it the easiest and quickest way to test the alternator is to disconnect the negative battery cable and it it dies its the alternator.If not it is the battery.

The other way would be remove the alternator and have it tested.

nhdungeonracer

Had a similar thing happen to my wife's Taurus a few years back. After buying a new battery, turns out the switch for the glove box light had moved, allowing the light to stay on even with door closed. Just got lucky when wife went out to car at nighttime, and barely saw the light shining around the door of the glovebox. After I put the switch back where it belonged, had no problems. Just wish she saw it before we bought a new battery [:@] Oh well.
So anyway, check for "anything" that could be drawing on the battery while the car is not in use.

Lennyseleven

I noticed that the defrost light was staying on all the time so I pulled the plug out of the back of the defrost button thinking that would help, the light is out now. But today I plugged in the connections on the back window and noticed a popping, like a connection was being made, and this was with the car off and the defrost button disconnected. I havent checked it with the multimeter yet tho...
Can anyone tell me which fuse is for the defrost( I dont have an owners manual), also the airbag fuse please.

thanks
Nick

roundman

look on the back side of the cover from the fuse panel which is located near your left knee in the lower dash. I believe there is a map there telling you which fuse is which.

VertStangGT86

You should also be able to take the positive cable off and check for current by bridging it with some leads and a multimeter. If something's drawing it should show up.

Lennyseleven

Hah, my fuse cover is missing as well!
I think ill check ebay for an owners manual


thanks again
Nick

Lennyseleven

Is it poss. that it doesnt have enough cranking amps? It has 500.
I took off the positive and there are no drains now.
What worries me is that when its running(this is with a charged battery) it will start high on the batt. gauge and slowly go down to around middle of normal, but when you run the windows or anything the gauge will drop, maybe this isnt a big deal but I dont remember this happening on any of my other cars.

thanks
Nick

VertStangGT86

When the gauge drops that just shows it's actually working cause it will drop. Mine doesn't move anymore ever since last year when I had some alternator problems. I wouldn't worry about the drop with the windows though. What you can do now is try removing fuses and seeing if it still draws, might be able to narrow it down some by doing that.

roundman

probably nothing to worry about, anytime you put a load on it the gauge should drop off but then go back where it was after you remove the load. check the voltage across the battery with the engine running, it should be up around 13.5-14 volts with engine just above an idle at 1,000 rpms. if not, then get someone at an auto parts store to check the alternator output.