Bad Alternator ?

Alexxn 00 Si · #1 12-23-2004, 06:44 PM

My 2000 Blazer LT 4.3.....noticed tonight that my dash lights were dim and I could hear a whining from my speakers, only had my headlights on....tested it with a Voltmeter and it read roughly 12.23 volts at idle BUT.....when I rev the motor it goes to 14 volts....could this be the alternator ? Battery is only 6 months old, AC Delco....

Thanks !

BlazerLT · #2 12-23-2004, 09:17 PM

Yip, the alternator is not producing the right voltage.

This could be caused by a bad battery with an internal short or the alternator has bit the bisket early.

I would get a warranty replacement. It is covered by a years warranty.

Alexxn 00 Si · #3 12-25-2004, 02:23 PM

Yep, alternator was the problem....got a Bosch rebuilt at NAPA (it's nice to have a buddy there !) and now it reads 14.7 volts at idle with EVERY accessory I could think of on plus the headlights.

Thanks BlazerLT !!!

BlazerLT · #4 12-26-2004, 04:22 AM

You are welcome!

Glad to see you happy.

Alexxn 00 Si · #5 01-08-2005, 06:15 PM

Well I THOUGHT all was well.....now all of a sudden when I am idling the Vots drop all the way down to 12 and then back up to 14......if you sit and idle about every 30 seconds or so this happens, the lights dim, and then it goes back up to 14.

New alternator gone bad ??? I am getting so frustrated with this truck now...

BlazerLT · #6 01-08-2005, 06:35 PM

I would get your battery tested.

If it will not hold a charge, the alternator will be constantly working to keep the battery up to snuff.

This will burn it out in short order.

Alexxn 00 Si · #7 01-09-2005, 05:36 PM

Battery tested 100 % OK....

blazee · #8 01-09-2005, 06:05 PM

Check all of your wires and connections, make sure they are tight and in good condition. Also make sure the mounting bolts are tight. Look and see if the belt shows signs of slipping.

blazee · #9 01-09-2005, 06:15 PM

Also make sure your battery is fully charged before you connect the new alterator, or your alternator will be DOA.

BlazerLT · #10 01-09-2005, 07:42 PM

Quote:

Originally Posted by Alexxn 00 Si

Battery tested 100 % OK....

Who tested it?

Did you hook up an voltmeter to it?

Alexxn 00 Si · #11 01-09-2005, 08:15 PM

I took it to Autozone and they checked it...

BlazerLT · #12 01-09-2005, 08:21 PM

Teheheh, don't trust them.

Take a voltmeter out and connect it to the battery when the engine is off, and again when it is running.

Alexxn 00 Si · #13 02-08-2005, 12:49 PM

Quote:

Originally Posted by BlazerLT

Teheheh, don't trust them.

Take a voltmeter out and connect it to the battery when the engine is off, and again when it is running.

OK now that we finally had a nice weekend I decided to dig into this again....Voltage at the battery with the engine/key OFF - 12.76 volts, Voltage at the battery with the engine RUNNING - 14.58 volts.....

I went ahead and got a warranty replacement alternator and installed it. Voltage reading with the new alternator and engine running is 14.61 volts.

STILL having the same problem, many times after coming to a stop and mostly at night the volts will drop down to 12, then rise back up to a little past 14. I am also noticing that when idling with the turn signals on the volts needle will bounce back and forth slightly...

Is any of this normal ? I NEVER noticed this before with my original stock alternator....

Any help is appreciated !

BlazerLT · #14 02-08-2005, 02:40 PM

The needle bouncing with the signal is normal, the dropping to 12v is not.

It ONLY happens at night?

Alexxn 00 Si · #15 02-08-2005, 02:42 PM

Yep...I've only noticed it in the evenings when my headlights/dash lights are on.......BUT doesn't do it everytime I stop either....

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