Bad alternator or battery?

[xanarchistx]

Hello everyone.

The problem that I am having is that I cannot tell if my vehicle is suffering from an alternator or a battery problem. I own a 01 GMC Jimmy 4.3.

What happened was this: As I was pulling out of a parking space, my battery light went on, and my car just stalled. The lights were still on, so I put the car into park, and then everything went out. I couldn't get my key out of the ignition, the lights wouldn't turn on, and I couldn't put the truck into any other gear. Then I got out, popped the hood, and put the support up. Once I did that, then the lights went back on. I went back into the car, put the key in the ignition, and attemped to turn the car on. The lights went on, the starter kicked, but the car wouldn't turn on. After a couple of minutes, the car then turned on, and I drove home.

Now, what do you think could be the problem? Alternator or battery? I just purchased a new battery about 2 months ago (maybe a bad cell?).

Also, I had the air conditioner on when this happened, so maybe that was a factor as well?

Any help would be greatly appreciated!

[CanukGMC]

Originally Posted by xanarchistx

Hello everyone.

The problem that I am having is that I cannot tell if my vehicle is suffering from an alternator or a battery problem. I own a 01 GMC Jimmy 4.3.

What happened was this: As I was pulling out of a parking space, my battery light went on, and my car just stalled. The lights were still on, so I put the car into park, and then everything went out. I couldn't get my key out of the ignition, the lights wouldn't turn on, and I couldn't put the truck into any other gear. Then I got out, popped the hood, and put the support up. Once I did that, then the lights went back on. I went back into the car, put the key in the ignition, and attemped to turn the car on. The lights went on, the starter kicked, but the car wouldn't turn on. After a couple of minutes, the car then turned on, and I drove home.

Now, what do you think could be the problem? Alternator or battery? I just purchased a new battery about 2 months ago (maybe a bad cell?).

Also, I had the air conditioner on when this happened, so maybe that was a factor as well?

Any help would be greatly appreciated!

Was it wet out when this happened? I highly doubt a battery issue here, when the vehicle is running the alternator will pretty much power the whole vehicle, the battery is just there to send the charge out to the proper area, unless the battery blew up or was removed it should have remained running (in most circumstances). If it was wet out you might have a short somewhere or a crack in your distrubutor cap which would cause the ignition to short and the engine to cut off and not restart for an indeterminate amount of time until dried and then it would fire fine until wet again. As well you might want to remove your battery cables, clean them with brake cleaner and a wire brush to make sure all the crud is out (do the cable ends AND batt terminals), even the slightest amount of junk in between the connection will randomly cause it to stop functioning like that, make sure you bolt them back on tight. hth

[xanarchistx]

Actually, it was raining cats and dogs the night it happened. So then it would most likely be a short?

[CanukGMC]

Originally Posted by xanarchistx

Actually, it was raining cats and dogs the night it happened. So then it would most likely be a short?

I bet you have a knick in your plug wire (coil to distributor) or a crack\bad seal in your distributor itself (or other than that maybe a crack\leak into your ECM). I'm betting distributor or the like. What happens is you get water into the distributor cap or the coil-to-dist-wire and it completely shorts the ignition out, it can even do it so bad that all you'll get is a click-click-click when turning the key, or the more likely crank-crank-crank but it never seems to fire. The water shorts the volts running to the plugs and it can't fire. It of course will dry out (sometimes quick, sometimes not, I've had them stay shorted for 2 hrs before, sometimes 30 secs, even stalled out while driving after hitting a puddle) on it's own but it's a pain in the butt when it keeps happening.

Easy temp fix to see if it's the issue?

-inspect the cap\wires for damage. None seen? Then buy a can of ignition protectant from autozone\canadian tire or the like and spray the heck out of your plug wires and dist cap. Keep driving as usual and wait to see if the problem shows up again (without rain) or if it does re-appear with rain re-spray the parts to seal them and maybe even spray the ECM (the computer). I've sprayed many of my distributors and had the problem go away instantly. Of course if you don't know the last time the cap\rotor\wires have been done it can't hurt to do em anyways and then spray them ontop of that. hth

[Jimmy58]

If your battery light came on it indacated that the battery circuit was shorted in some fashon. I would first check the 175 amp fuse under the battery box on the rad support. You might have a bad connection there. Second I would bring your truck Or your alternator to an alternator shop(NOT the dealer) and have them test the regulator. These trucks have a 130 D alternator and have one of several regulators in them that are very sensative to shorts and surges. If the regulator goes there is a possibility of sending 3phase AC power into your vehicle's system. this will cause all kinds of problems ASK ME HOW I KNOW. You can easily check your battery by bringing it to VIP or other shops like that and have them load test it.
Good luck
Nick

[cheerish]

hi i have a 98 monte carlo and it started with my voltage light coming on. so i took it to auto zone and had the battery tested and the alternator. they said they seemed to think it was the connection wires so after cleaning those it was just fine. the amps read the same coming and going from the battery and alternator. but when i went back out to start it again i started having the same problem. even purchased a new battery and that didnt fix it... one time it works fine and then the next the light comes back on and my inside light will dim along with my head lights when the car is given gas... any suggestions on what to do now????

thanks alot

[trannyman52]

you should really re-check battery terminals for a poor connection,,,check alternator output with a vom ,,,engine running,, lights,,,blower ,,on,, voltage should read 14 volts or better,,,battery should read 13.5 volts with car shut down,,,nothing running.....
If alternator reads below 13.5,,,there is a problem with it.....