Another charging issue on a 83' Diesel Sub

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bigjeepinmike

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mike
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1983
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suburban
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6.2d
Sorry to beat a dead horse but i searched around to cover all the basics on my non charging sub.

A little background on the new to me Sub. Its a 1983 k20 Suburban with the 6.2 diesel, banks kit, etc. Its in remarkable condition having been stored indoors since 2005. I bought it from a fellow who went blind. He had issues with the headlights so he took the dash apart to replace switch, and then the switch plug. I confirmed with schematics that all was wired correctly, phew. Truck runs great but I noticed it wasnt charging too. Deduced that it was the fusible link shared by both circuits. Replaced the light feed and alternator sensing wire fusible links with their own properly sized link. That was a dang contortion act! Lights work, no dash lights though, dome lights work though under dash light stays on but dims when the door is shut. Figure its another problem to deal with in future.

Not charging still. Batteries were trickled charged. Battery wire shows battery voltage, sensing wire shows battery voltage, brown keyed wired has shown anywhere from 6.8-10.4v. Now if I jump pin one and two she starts charging at 14v, remove jump, nothing. What does this tell me? Is the internal regulator bad? Is the brown keyed voltage too low? If it is, where does the brown wire go after it enters the cab? I have a schematic i downladed but because its broken into multiple pdfs im having a bear of a time tracking it beyond the bulkhead. Thanks for your input.
 

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SirRobyn0

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Rob
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C20
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305
@bigjeepinmike The alternator and internal regulator are fine. You proved that when you jumped the terminals.

Both #1 & #2 terminals need to have 12 volts at them. #1 terminal (I'm sorry I don't remember the color, but may well be brown as you said) should have keyed on 12 volts. You have less than that. Is 6.8 - 10.4 enough to get it charging I don't really know, but from what you have said it looks like it's not. I would be tracing that wire. There are wiring diagrams in the reference section on this forum.
 

bigjeepinmike

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wa
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mike
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1983
Truck Model
suburban
Engine Size
6.2d
Update, bad alternator. Regulator would draw key wire voltage down to 3.4v when i would connect sensing wire. Was weird but charging now!
 

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