GM alternator wiring

Discussion in 'General Tech' started by rattlecanpaint, Sep 2, 2012.

  1. rattlecanpaint

    rattlecanpaint Well-Known Member

    Joined:
    Apr 18, 2005
    Location:
    Winston Salem
    I'm helping my buddy wire is '46 Chevy pickup/'92 S10 hybrid. Basically it's a '46 Chevy pickup body on a '92 S10 frame with a 350 in it. My problem is the alternator. It has 4 wires in the connector labeled f, s, p, l. I've searched until I'm blue in the face and have come up with conflicting reports of how to wire the thing. The alternator is off the 4.3 liter that was in the s10 and the wiring harness looks to be only using the "S" and the "P" terminals. One goes to a switched 12 volt source and supposedly the other goes to a gauge or idiot light with resistor in parallel (in case the bulb goes out). Is this right or do I use the "F" to switched power and "S" to gauge/idiot light?
     
  2. rattlecanpaint

    rattlecanpaint Well-Known Member

    Joined:
    Apr 18, 2005
    Location:
    Winston Salem
    I guess I don't feel so bad now........
     
  3. 1badz2nv

    1badz2nv fustercluck extraordinaire

    Joined:
    Jan 3, 2008
    Location:
    Dunn
    only thing i could find......maybe it'll help cs144 alt.jpg
     
  4. rattlecanpaint

    rattlecanpaint Well-Known Member

    Joined:
    Apr 18, 2005
    Location:
    Winston Salem
    Ok so now I've read that on of those that go to a idiot light must have a resistor in parallel so when the bulb burns out it won't fry the alternator. Heard of this?
     
  5. Caver Dave

    Caver Dave Just holdin' it down here in BFV Moderator

    Joined:
    Mar 10, 2005
    Location:
    Hooterville (24171)
    Guessing this is a CS-series alt?
    On my CS-144, I added a resistor to the ignition hot going to "L" (lead to "F" is dangling... didn't want to fiddle with the OE (40+ year old) wiring back to the idiot lamp :rolleyes: )
     
  6. MarsFab

    MarsFab Will work for money

    Joined:
    Oct 24, 2007
    Location:
    Harrisburg, NC
    Here's an excellent tech article from pirate.

    http://www.pirate4x4.com/tech/billavista/Wiring/Part2/

    1) Connect the alternator output terminal (B or Bat) to the electrical system's main distribution point (bus bar, junction, etc.) Less optimal alternatives that will work include connecting it to the battery + terminal or a terminal on the starter motor that also connects to the battery + terminal.

    2) Connect the L terminal to a source of switched ignition power through an indicator lamp wired in series. Also connect a 50 Ohm resistor in parallel with the indicator lamp so that if the bulb burns out, the alternator will still be excited.

    3) Ensure there is a good ground connection between the bare alternator case, the mounting bracketry and the engine block/heads and/or install a dedicated ground wire from the engine block to the alternator's ground terminal (if it has one).
     
  7. rattlecanpaint

    rattlecanpaint Well-Known Member

    Joined:
    Apr 18, 2005
    Location:
    Winston Salem
    Would a volt gauge be OK instead of the light?
     
  8. catfishblues

    catfishblues Well-Known Member

    Joined:
    Jul 26, 2005
    Location:
    Pfafftown, NC
    No. It will read 0 until the alternator fails, then it would go to 12v. That's the point of the light. If the alternator fails, the field becomes de-energized and the light will see it as a ground, coming on. You've got 12v from the battery on one side, and the field will create 12v on the other side, making the light think it's at 0v. When the alternator quits producing current, you will have the 12v from the battery on one side and ground on the other, illuminating the light.
     

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