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Old Apr 11, 2009 | 06:24 AM
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Default Low voltage

Well going to probrably swap out the alternator, but my car is using a alternator relocation bracket. My alternator is only putting out 12.2 volts at the alternator and my pcm is not getting enuff juice(11.1 volts). My question is anyone running a aftermarket alternator with all their additions(standalone 4l80e tranny computer, boost a pump, additional fuel pump, inj driver, eboost 2, meth kit, and etc on the car).Hopefully its the alternator, anything else i should look at. Think a bad ground could be a culprit. The person who did the turbo install really did a half-@ss job and have spent the last few months cleaning it up. Frost and Khaos have been helping me get the thing back into shape.

Last edited by sagres; Apr 11, 2009 at 07:46 AM.
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Old Apr 11, 2009 | 07:34 AM
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i dont know why but my pcm and scanmaster show 1 volt less in the car than it does at the battery alternator or fuse boxes under the hood. You can use a truck alternator if you have room....the case is a little bigger than ours and only uses the front 2 bolts which is all i use anyway. i have the Hummer alternator...it is the same as the truck alternato just 145amp vs truck 135 amp vs fbody 105 amp.
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Old Apr 11, 2009 | 08:42 AM
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just somthing stupid did u check the plug that goes to the back of your alt.
there should be a little brown wire in that four prong plug it should see curent when the key is in the on postion (forward) if no current the alt will not kick on and charge the system
Good luck
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Old Apr 11, 2009 | 12:33 PM
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its charging but only like 12.2 volts. Should be over 13v
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Old Apr 12, 2009 | 04:30 AM
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had the same problem a while back, it wound up being the plug with the single red wire, think its called the signal wire. there is an upgraded one availible that is a thicker gage. I prob. pulled on mine a little during the removal and install of my latest engine
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Old Apr 12, 2009 | 06:15 AM
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I'd double check all the grounds to be on the safe side. What about the belt? Is it good an tight and not slipping at all? Do you still have a tensioner on your setup?
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Old Apr 12, 2009 | 08:49 AM
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Originally Posted by lmt0705
had the same problem a while back, it wound up being the plug with the single red wire, think its called the signal wire. there is an upgraded one availible that is a thicker gage. I prob. pulled on mine a little during the removal and install of my latest engine
I have to agree on the thickness of that wire, its very tiny (22ga). Dont know why they didnt use a bigger wire.
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