Is my alternator dead?

Well, while driving home today on the highway. All my gauges on my dash just went dead on me. It was about three miles away from my house. Good thing it wasn't far away when this happened. I got home, turn off my engine, try to restart my car (a 1999 GMC Jimmy 4WD), and it did not start. I took out my multimeter, did a reading on my battery, and it was reading at 8 volt. I use my wife's car to give my car a jump start and it started. Then I took off the cable, did another reading with the multimeter, and it wasn't still giving me a reading at 12V to 14V. With the cable connected from my wife's car while running, all my electrical stuff were ok. With the cable off, all my electrical stuff were fighting for power. I did this with my engine running and not running. Would it be the alternator or a fuse link? I check all the fuses and everyone was ok. The only thing I could think of now would be the alternator, and I took it off already. Going to take it to a shop to check it out for me tomorrow.

Could be your alternator...could be your battery. If you hadn't had your battery replaced in a while, that may be it. You could just have some dead cells in your battery. Just because a battery reads between 12-14 volts doesn't mean it's good. So check out both things.~The Rookie~

Rookie of the year that is...

Don't let the smoke out of your equiptment..it doesn't go back in.

Yes it was the alternator that was bad. A friend helped me install a new one today along with a new belt. I also found out GM's alternators don't last too long. I mean my car is only five years old and that is kind of short for a alternator to die so fast. My dad is still driving his 1990 Toy pickup V6 4WD with almost 200K miles without any alternator problems yet. I also heard about alternator problems from other Blazer, S10 and Jimmy owners on the net too the other day. My friend and I change everything for $150. Better then taking it to a shop for almost $500.

Vansolo wrote: I mean my car is only five years old and that is kind of short for a alternator to die so fast. My dad is still driving his 1990 Toy pickup V6 4WD with almost 200K miles without any alternator problems yet.

That is relative to how you use your vehicle as well. If your vehicle is so equiped with after market devices such as high power stereo, lights, etc. This will play a large role on the service life of the alternator. The biggest killer of any alternator is from those people who do not know how to jump start a dead vehicle, or to place a battery charger in the circuit path. 1. You never jump start a newer style vehicle. Regardless of what people tell you. It does not help in the least, other than the fact your vehicle is running now. Opposed to dying later . . . 2. Remove the negative battery terminal from the battery when charging at low current rating of 2 amps. Standard SLI batteries cannot endure large amounts of in rush current to be replaced, once fully depleted. Regards EVIL Teken . . .

Teken wrote: 1. You never jump start a newer style vehicle. Regardless of what people tell you. It does not help in the least,

How do we jump start a newer style vehicle? I did that on my previous car. After I got it from the factory for only 1 month, I forgot and left my dome light on and checked my car after 4 days. Battery went completely dead. AAA came and jump started it and I used the car for 3 more years until my lease ran out without any problems. I would like to learn the proper way if jump starting is not proper. Thanks.