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Alternator stuffed or just regulator?

Posted: Tue Jun 02, 2009 3:41 pm
by mike_nofx
Vehicle is 90' Suzuki Sierra.

The alternator is no longer charging, and battey light is visible on dash. At higher revs, the battery light will occasionally turn off, though battery is still not charging. confirmed with a multimeter.

I have disconnected the charge wire (from battery positive to alternator) and connected a multimeter to the alternator to check voltage, at idle i am getting around 1 volt, and at 4000rpm i am getting around 5 volts.

Would this be a stuffed regulator? and if so, are these easily sourced from auto parts stores?

If not the regulator, what else could it be?

Thanks
Mike

Posted: Tue Jun 02, 2009 4:02 pm
by chimpboy
I would just grab a used alternator from a wrecker for twenty bucks and drop it in. It could be brushes, wiring/connections, regulator...

What are your voltages when everything IS connected together?

Posted: Tue Jun 02, 2009 4:40 pm
by stuee
As far as I know regulators work using a feedback control loop. They read the voltage of the battery and this voltage determines the output of the alternator (obviously rpm will determine how much the alternator can pump out too).

So by removing the battery to take a measurement you will not get an accurate reading from the alternator.

Posted: Tue Jun 02, 2009 7:19 pm
by mike_nofx
With everything connected up, engine running, and multimeter on battery it reads around 12.5V the same as when engine is off.

Even with high rpm there is no change.

I have removed and opened alternator, and brushes do appear fine.

Mike

Posted: Sat Jun 13, 2009 7:34 pm
by Fpv_83
Gday mate

I just picked up my alternator as i had to get it rebuilt.
I had EXACTLY the same problem as you!
12V and the light was on on the dash.

Havnt had time to put mine back on but my auto elecy tells me it should be perfect.
Cost me heaps but coz everything had to be replaced coz mud n s*@^ killed bearing n that.
Bout $260 but hopefully no more headache

So i recommend you get yours rebuilt or if you fell better get a 2nd hand 1 from a wrecker. Dont get a swift 1 with the multi groove belt pulley!!!!
Learnt that the hard way, pulley alignment doesnt happen
Cheers
Mark

Posted: Sat Jun 13, 2009 7:34 pm
by Fpv_83
Gday mate

I just picked up my alternator as i had to get it rebuilt.
I had EXACTLY the same problem as you!
12V and the light was on on the dash.

Havnt had time to put mine back on but my auto elecy tells me it should be perfect.
Cost me heaps but coz everything had to be replaced coz mud n s*@^ killed bearing n that.
Bout $260 but hopefully no more headache

So i recommend you get yours rebuilt or if you fell better get a 2nd hand 1 from a wrecker. Dont get a swift 1 with the multi groove belt pulley!!!!
Learnt that the hard way, pulley alignment doesnt happen
Cheers
Mark