alternator or battery?

[fenderman]

That trick works on older cars but with the sensitivity of the computers and such I wouldn't recommend disconnecting the cable while the car is running. Debate me on this if you must but I stand behind that statement and is something I will never do. Get a voltmeter and check your battery once the car is running. If it reads significantly under 13.5V, the alternator is bad. I also know Auto Zone will do a free test for you if you do not have access to a voltmeter. But don't disconnect the cables while the car is running.

[defrag]

i got it towed to a shop today and they told me the "computer" is bad, said it would cost about $400 to replace and then they would be able to scan the car and findout what else is wrong. It sounds like a crock of bull to me. what do you guys think?

[Tru2Chevy]

I suppose it could be the computer causing the trouble (they can be quite cranky when they want to), but I would ask the shop what all they tested to come up with that conclusion. Did they test the battery, alternator, connections? What about the fuel pump?

I know the 3rd and 4th gen electric fuel pumps should be audible from inside the car. Turn the key to the run position and listen for a buzzing/whirring sound for 2-3 seconds....that's the fuel pump priming the fuel system.

- Justin

[ February 06, 2004: Message edited by: Tru2Chevy ]</p>

[CamaroRob97]

<blockquote>quote:</font><hr> I guess it doesn't matter now that you switched both parts out but if you want to test if it is your alternator or battery you can get the car started, then remove the negative battery cable. If the car continues to run the alternator is good. If it dies the alternator is bad. <hr></blockquote>
Nooooo! Never do on a computer controled car. YOu will be replacing the pcm if you do that.