Alternator help

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Jul 4, 2002 | 01:28 AM

GlockLT4

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From: Dallas TX

Alternator help

Ok, so the power output from an alternator should be around 14.4 volts right? Not my vette (sorry), but i know you guys will know this. With the blazer off, the system voltage is 11.89volts. The alt is putting out the same amount when it's on. With the blazer off, the alt is putting out only 6 volts.

I just put a new alt on too... so what's the deal? Took the battery to be tested, they said it was ok but gave me a new one anyway. Reason for changing the alt was the "battery" light turned on in the dash. After replacing the alt, the battery light went away, but voltage is still really low and the car is idling twice as high to try and get voltage.

any ideas? I guess i can try another alt.

[Modified by Glock'94, 12:02 AM 7/4/2002]

Jul 4, 2002 | 03:31 AM

jfb

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From: Cincinnati, Oh USA

Re: Alternator help (Glock'94)

What do you mean by , "With the Blazer off the alt is only putting out 6 volts"? When the engine isn't running the alternator has no output.
If your battery voltage is 11.89 volts, then you have a discharged battery and it needs to be charged back up. If the voltage across the battery does not change when the engine is running, then the alternator has no output or its fusible link is blown.

Jul 4, 2002 | 03:34 AM

GlockLT4

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From: Dallas TX

Re: Alternator help (jfb)

What i mean by it is exactly what i said. It makes no sense. The voltage is low. I thinking there is a bad connection somwhere on the power wire from the alt.

The power at the alt should still show what the battery is registering when the engine is off.

Battery is brand new.

Jul 4, 2002 | 03:41 AM

jfb

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From: Cincinnati, Oh USA

Re: Alternator help (Glock'94)

The evidence is very clear, .....you have a blown fusible link. follow the large output wire from the alternator back to the battery and you will come across the fusible link. You can prove this by disconnecting the output wire from the alternator and measuring the resistance from the battery + to the disconnected wire. It should be zero ohms (or the same as with the ohmeter leads shorted).

Jul 4, 2002 | 03:44 AM

bill mcdonald

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Re: Alternator help (Glock'94)

FJB helped me out with an alt problem a while back, He mentioned the fusable link. While I was looking at what a PITA it would be to replace/find it, I stumbled upon my connector at the alternator. My wire was corroded and turned green behind the boot. I snipped the lead off, put on a new connector and the power was back to normal.

It might be worth a look.

Jul 4, 2002 | 03:50 PM

dantos

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From: indiana

Re: Alternator help (bill mcdonald)

I had the same problem with my 89; Lost two alternators before I found it 4 years ago. No load on the alternator equals blown diodes.

Jul 4, 2002 | 04:01 PM

GlockLT4

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From: Dallas TX

Re: Alternator help (dantos)

Lol, i figured it out. The stupid connector that goes into the alt wasn't in all the way :blueangel: . The computer couldn't turn the alternator on :).