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Discussion Starter #1
I recently bought an 83 s10 swapped with a throttle body 350. But they changed the throttle body out to carburated. The wires were a mess when I got it but we went through got rid of a bunch of unneeded b.s. Now I've got one problem. For the life of me I cant get the altenator to charge. I've put 3 used alternators on and a brand new one. The brand new one is on now. After removing all the wires from the altenator and testing straight off the hot post of the alternator I get .83 v. When testing with everything hooked up I'm staying at around 11.9 v. Now I'm lost on what could be causing this problem. I am to understand that I should be seeing around 13.5 v when running. I see about 11.02v with headlights on. Please ask any questions and I'll do my best to answer quickly so I can get this problem taken care of. I'm new to the v8 swapped s10 stuff but I do know a bit about mechanical work.
 

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94 4x4,01 Blazer
2001 Blazer 4dr 4wd LT
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1,253 Posts
to eliminate the first issue- take alt to parts store and have them test it. if it tests good-more than 11.9- look at your pulley sizes on engine.
 

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Discussion Starter #4
to eliminate the first issue- take alt to parts store and have them test it. if it tests good-more than 11.9- look at your pulley sizes on engine.

Do you think the pulleys on the engine might not be turning the altenator quickly enough to produce charge?
 

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94 4x4,01 Blazer
2001 Blazer 4dr 4wd LT
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1,253 Posts
could be- have it tested first- you might have underdrive pulleys as a horsepower gain - does happen .
 

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Is the alternator an 83 10 or 12 SI or a later CS? You can tell by the plug on the back. An SI has a 2 wire flat connector for the sensor and idiot light. The CS has a newer style connector that can handle 4 pins, but usually only the same 2 are connected.
The SI needs the #1 pin (the left one) connected thru an idiot light to work and the other small needs to be connected to the battery. Usually at a junction block or some other B+ red wire as far from the battery as possible to sense how much current the electrical system needs.
A CS is wired the same but the wires are L and S (light and sensor) which are the 2nd from the left and the right one.
If these aren't connected it won't charge properly.
342274
 

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Discussion Starter #7 (Edited by Moderator)
Is the alternator an 83 10 or 12 SI or a later CS? You can tell by the plug on the back. An SI has a 2 wire flat connector for the sensor and idiot light. The CS has a newer style connector that can handle 4 pins, but usually only the same 2 are connected.
The SI needs the #1 pin (the left one) connected thru an idiot light to work and the other small needs to be connected to the battery. Usually at a junction block or some other B+ red wire as far from the battery as possible to sense how much current the electrical system needs.
A CS is wired the same but the wires are L and S (light and sensor) which are the 2nd from the left and the right one.
If these aren't connected it won't charge properly.
The alternator is for a 95 model. These photos seem to be according to your response a CS. Thank you.

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Appears to me that the brown one is correct, but the red one is not there.
Usually there is a pink wire only if there is no alternator light. The larger S terminal is the sense wire which determines the alternators output based on what the voltage is in the battery circuit. That's why it is a red wire. Because it's part of the B+ wiring system. (Red also means always hot)
 
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