Complete Electrical Failure

[ThuginThaEast]

Hello everyone i am completely need to forums and i really need help with my 99 olds Aurora.

About a week ago i was driving my sister to her doctors appointment, but when i stoped at a light my car went nuts. i was the weirdest thing>> the RPM, mph, and all the other needles started jumping back and forth untill my car finally shut off. i was able to get the car off the road and was picked up just to go back to my car 3 hours later. when i went back i jump started it with my moms 01 Jimmy and it started right up so i drove i to my sisters doctor's office, shut it off and went in. came back out not even 5 mins later and the car would it start. Figured i was the battery so i jump started it and it ran but as soon as i took off the jumper cables it halted to a stop. Restarted it a few times but the problem continued. i watched the DIC and the voltage was at 13.5 untill i disconeccted the jumper cables them it would steadly go down to 10 volts and by 9 the car would stuggle to stay on. I ended up leaving it and goin back a few days later...i had to drive it in 1st and 2nd so the RPMs would be higher just to keep the battery at 13volts.
That was the most confuseing thing i have ever seen a car do. So now my question is would the problem be my alt. or my battery or something completely different?

Oh and throughtout the whole thing the car didn't give me any clues or warnings!!!

[baron1701]

The cheapest way out would probably be the battery. I would disconect the battery from under the back seat and bring it to an autozone or advance auto and have it tested. It will cost nothing and narrow the problem down to the alternator. Replacing the alternator is a pain but can be done with basic tools and a couple hours.

After re-reading the post it does sound like an alternator issue. There may be a loose ground or short somewhere. Be carefull though, if you keep running it with a 'blown' alternator you run the risk of doing some damage to the electrical system. It wouldn't hurt to check the battery anyway. How many miles? The OEM alternator usually goes to about 100,000 or so. Good luck and welcome to the forum.

[ThuginThaEast]

thanx yea i figured it was the alt. and i was planing on to get the battery tested but i just haven't had time.

the car has about 93,000 miles on it but it the second motor in it. the first motor seized at about 87,000miles and the 2nd motor only had 72k miles but i am having more problems with this motor then i ever did with the 1st motor. i blame it on the mechanics who sold me the engine but theres nothing i can do now