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Old Apr 9, 2012 | 05:36 PM
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Default alternator hiss

i have a battery drain ( sitting for 2 days and compleatly dead) went under the 99 SS today and i can hear a electrical hiss comming from the alternator (car off). saw that the single red wire comming from the alt was cut open. i put a test light to it (light did not come on) and the hissing stopped but the hiss comes back as soon as i remove the test light ...could this be my battery drain and how do i solve the problem??

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Old Apr 10, 2012 | 10:27 AM
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Make sure it is the alternator, disconnect the power wire from the alternator and if the sound goes away you may have a bad regulator inside the alternator. Try replacing it and see what happens.

Your description is too hard to diagnose over the internet beyond that. But first, confirm it is without doubt the alternator by disconnecting it.

I have heard of alternators draining batteries many years ago but haven't every actually encountered it. As far as the electrical hiss... never heard of that one either. But like I said, the first thing you need to do (in any diagnoses) is confirm.
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Old Apr 10, 2012 | 01:33 PM
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Okay I unpluged the power cable to the alternator and the hiss did stop , connected it back in and of course the hiss is back...so need to replace my alt? ...i guess i will leave it unplugged and check the voltage on the battery after it sits for a few hours to make sure thats whats drainning my battery..if i want to replace the single red wire , where does it go to ? The computer ? ...
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Old Apr 10, 2012 | 02:46 PM
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Originally Posted by Big Black SS
Okay I unpluged the power cable to the alternator and the hiss did stop , connected it back in and of course the hiss is back...so need to replace my alt? ...i guess i will leave it unplugged and check the voltage on the battery after it sits for a few hours to make sure thats whats drainning my battery..if i want to replace the single red wire , where does it go to ? The computer ? ...
Yes try another alternator. I believe the wire runs straight into the battery terminal. Haven't really looked at mine in almost 2 years.
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Old Apr 10, 2012 | 02:54 PM
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Yes that one does goe straight to the battery but i was asking about the other small single wire
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Old Apr 10, 2012 | 02:58 PM
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Just for ***** n' giggles-you aren't running an ipod mod are you? Don't get caught up on the "hiss", it may have nothing to do with your battery drain.
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Old Apr 10, 2012 | 03:05 PM
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No ipod mod , have a amp hooked up but its been unplugged for a month...
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Old Apr 10, 2012 | 03:26 PM
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And also , if i get the truck alt. From a pepboys (i can get 20% off) what year do i ask for ?
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Old Apr 10, 2012 | 03:35 PM
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Originally Posted by Big Black SS
And also , if i get the truck alt. From a pepboys (i can get 20% off) what year do i ask for ?
I asked for a 2003. Ask for the 145 amp, make sure it's the 4 pin connector when you open the box.

Replace the connector too
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Old Apr 10, 2012 | 03:40 PM
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K thanks for your help ...and i will let you guys know the outcome ....
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Old Apr 10, 2012 | 05:26 PM
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Originally Posted by Big Black SS
Yes that one does goe straight to the battery but i was asking about the other small single wire
It goes up the wiring harness to the computer. Get a new connector and it will have roughly 6-8" of wiring already. Cut your wire and wire in the new connector and you are good to go.
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Old Apr 10, 2012 | 09:36 PM
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Got home from work checked the volts at 2:36pm and it was at 12.4 , unplugged the alt.power wire checked the volts at 5:02pm it was at 12.3 checked again at 7:14pm and its still at 12.3 volts ..so im guessing the alt is draining my battery..
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Old Apr 10, 2012 | 11:13 PM
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Originally Posted by Big Black SS
Got home from work checked the volts at 2:36pm and it was at 12.4 , unplugged the alt.power wire checked the volts at 5:02pm it was at 12.3 checked again at 7:14pm and its still at 12.3 volts ..so im guessing the alt is draining my battery..
Sounds like it! Glad you found it man.
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