Alternator issue on Scout II

Discussion in 'General IH Tech' started by Glenn Smith, Feb 27, 2018.


  1. Glenn Smith

    Glenn Smith Farmall Cub

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    Ok so I am almost finished with all the bugs on my 77 Scout II for now lol.. I am trying to make sure the wiring for it is correct. Right now I am having to charge the battery every couple of days. I am looking for advice on the wiring. Right now the alt. has a red wire coming from the post back toward the firewall and a white wire going to the guage it looks like. That is the only wires that I have on it currently. I am looking for what wires do I need and where should they go. I believe the wiring is a quickwire or ez wiring kit.

    Also ammeter gauge stays in the middle even with the car off

    Thanks again yall are always helpful!
     
    Last edited: Feb 27, 2018
  2. MrKenmore

    MrKenmore Y-Block King

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    10SI Wiring.jpg

    This should provide some general guidance. Note it is not exact how the Scout is wired but you get the concepts.

    Can you take a pic of your setup. Sounds like you are short a wire.
     
  3. Bob BMW

    Bob BMW Binder Driver

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    You have a SI type alternator with internal regulator? If so the big red wire goes from the post to one side of your amp gauge. The other side of the amp gauge should have a big wire that goes to the battery connection on your starter solenoid. This will take care of the alternator output to the battery charging circuit. When you say it looks like where a wire goes someplace. You need to know for sure.

    Now, there should be a two pin connector that will plug into the alternator. If your wiring harness doesn't have one then this is something that needs to be corrected. But, the alternator has a #1 lug and a #2 lug that the connector should mate with. #2 lug is the remote voltage sense lug and goes to the starter solenoid battery connection. This big screw / bolt terminal on the solenoid is the same one that the amp gauge wire and the big battery cable connects to. The #1 alternator lug goes to the ignition switch through an idiot light or a resistor of some sort. It gets 12 volts applied only when the ignition switch is on. Yes a light or resistor are very important. This #1 wire is what causes the alternator to start charging.

    This wiring diagram may not be for a Scout but it is simplified enough so that most people can follow it.

    Thanks Mr. Kenmore. We duplicated but between the two of us he has plenty of good information.

    Good luck.

    Bob

    upload_2018-2-27_8-51-4.jpeg
     
  4. scoutboy74

    scoutboy74 Lives in an IH Dealership

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    And not to put any added pressure on you, but just so you know, you're sending your battery to an early grave by continuing to drive the vehicle with a non-operative charging system. If you have to drive the rig, that's one thing, but if you don't have to drive it, you'd do well to get the battery charged up and then park the truck until you know that the onboard charging system is working.
     
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  5. Patrick Morris

    Patrick Morris Lives in an IH Dealership

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    Meaning what? That you aren't seeing a discharge? I'm not sure how sensitive those gauges are.

    How old is the battery? If it was my truck I'd make sure the battery was in good shape before messing with the wires too much. (Can't hurt to check for something obviously wrong with wiring of course.) You didn't mention how you determined that the battery needs a charge every few days. Voltage is dropping below 12.5v? Engine just starts cranking slowly? Doesn't crank at all?

    Have you disconnected the battery after a full charge to see if it holds its charge while isolated?
     
  6. Glenn Smith

    Glenn Smith Farmall Cub

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    The Battery is brand new
     
  7. Glenn Smith

    Glenn Smith Farmall Cub

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    So I should have one going to the starter correct? Or the Solenoid?
     
  8. Bob BMW

    Bob BMW Binder Driver

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    Yep, and possibly getting stranded someplace because of a dead battery not being able to run the coil / distributor system. Been there, done that more than once!

    Bob
     
  9. Bob BMW

    Bob BMW Binder Driver

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    Solenoid. Or to be more correct. Starter Solenoid.

    When you say one, what do you really mean though?
     
  10. MrKenmore

    MrKenmore Y-Block King

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    If the config is stock (which I am not sure it is) you would have your big #10 wire off the rear post on the alternator going to the bulkhead connector. That's circuit #2. Inside the cab that goes to the negative side of the ammeter. Sharing that post is the feed to the always on side of the fuse panel (circuit #14A). Keep in mind the circuit numbers I am telling you are for later model scouts and yours may be slightly off but the pathway is the same. Your battery takes a hop skip and a jump by going to the starter solenoid, then from that shared post to the bulkhead connector, then once inside to the positive side of the ammeter terminal.
     
  11. Patrick Morris

    Patrick Morris Lives in an IH Dealership

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    Well that's one less worry. I still don't understand the significance of your comment about the ammeter needle. With engine off, it should be in the middle. Or were you just trying to say that the needle never moves at all?

    Did you get this from his ammeter gauge comment? I have to admit, I don't know how the gauge would perform if the alternator wasn't working, but I'd assume it would move into the "discarge" direction while the engine's on.

    I think the OP should check the voltage while running. It's probably the best test of the charging system. Should be something over 13v, as we all know.
     
  12. Glenn Smith

    Glenn Smith Farmall Cub

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    Got it working guys Thanks! I was missing the wire from the alt. to the starter. Works like a champ now
     
  13. Bob BMW

    Bob BMW Binder Driver

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    Good to hear you got it working, Glenn. And a big thanks for getting back here and letting us know.

    Bob
     
  14. scoutboy74

    scoutboy74 Lives in an IH Dealership

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    No, it was a hasty conclusion I lept to based on his having to charge the battery every other day or so. There's really only three reasons why that would be necessary. 1. Bad battery. 2. Parasitic drain. 3. Malfunctioning charging system. I had a 33.3333333% chance of being right and a 66.66666% chance of being wrong, but I'm more of a glass 1/3rd full kind of a guy.
     
  15. Patrick Morris

    Patrick Morris Lives in an IH Dealership

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    Isn't that a great feeling? :)
    I guess we were all thinking the same thing in one way or another.

    Come to think of it though, last year when my Scout's system started acting wonky, e.g. slow cranking on starts and low and fluctuating voltage while running, it turned out in the end that my alternator was fine but the battery was on its way out. Yet I was mostly suspicious of the alternator. I assumed that low running-voltage means bad alternator. So I learned to keep an open mind but should first suspect the battery. :cornfused:
     
  16. MrKenmore

    MrKenmore Y-Block King

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    Nice! Sounds like you were missing the sense wire. Certainly need that. Good luck and thanks for closing out the thread!
     

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