delco 12SI (GM 3 wire) Alternator swap.

Discussion in 'Interior/Electronics' started by junktown5852, Jan 29, 2013.

  1. junktown5852

    junktown5852 Newbie

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    Location:
    colorado
    Truck:
    81 hilux
    I looked for weeks trying to find a thread anywhere that just had a "how-to" on swapping the old weak toyota charging system for a GM 3 wire, with no luck other than 84-95 RE engines. Since driving a fenderwell-less Lux in wet weather seems to kill the factory mechanical voltage regulator (twice now..), I decided it was time to just throw that **** out. SO.. Here's a how to..

    Now you can get the brackets for a direct bolt in from Trail Gear for 44.00$
    Performance Components | Toyota, Suzuki Samurai, and Jeep Off Road Parts
    or the LC engineering brackets for 42.00.
    Alternator Bracket Kit(GM 1 Wire) - 20R/22R/RE/RET
    I would recommend buying the brackets and saving your stock stuff.


    But you can also Ghetto them up by cutting the lower bracket to fit the lower alternator tab and welding a front support piece to it. and extending the upper bracket by about 1 1/2". the upper requires some test fitting with the power steering bracket. i had to notch my PS bracket and reshape the upper ALT. bracket. you can look at the Trail Gear or LC brackets to get an idea of how they should look. Ill try to throw some pictures up of mine. I didn't even think to take pictures until after i was finished installing. My setup even lets me use the stock belt.

    Now once you get the alternator mounted comes the wiring. Dont get discouraged by the mess of wires running to that old crusty mechanical regulator because you only need two of them, and a $3.00 pigtail for the 12si alternator.
    Here goes:
    Terminal 1 on the alternator goes to your toyota fat yellow wire(8-10 GA)
    Terminal 2 on the Alt. goes to the Fat white wire on your truck(also 8-10 GA)
    Finally run an 8GA wire from the Alt battery lead to the battery + terminal.

    As for the rest of the wires, I trimmed them back and sealed them up, but i wouldn"t recommend this.just seal everything off as best as you can and save your old parts for spares just in case.

    I know this isnt the most comprehensive "How-to" guide but any questions feel free to ask and ill do what i can to help.
     
  2. junktown5852

    junktown5852 Newbie

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    Also, this cost me about 80 bucks total. Using a 78 amp alternator from oreilly's.
    More than doubled my idle charging amps, and now I can run lights, heater, and wipers all at once!!
     
  3. Ramrod

    Ramrod Member

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    Location:
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    Truck:
    77 pickup
    Ive done a quick youtube vid of it already, but for the first gen Pick ups
     
  4. BILLYDEAN

    BILLYDEAN Newbie

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    So it's the white wire coming out old volt reg that I hook to thermal 2? And the stock big white wire tht goes to battery
     
  5. 1980mini

    1980mini Member

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    Location:
    Washington
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    1980 gen1
    id use a 1 wire gm run to the battery and bam done and every thing else to battery also. i have a 3 wire in my 80 and it wont charge worth a ****
     
  6. first80toyota

    first80toyota Addict

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    Location:
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    '77 Hilux
    I put a 100 amp 3 wire from summit in my '77 and it charges amazingly! I ran new wiring to the battery for it using 4 gauge wire.

    I used a 3 wire because they way I hooked it up my charge light still works..:waytogo:
     
  7. Inertia

    Inertia Enthusiast

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    Ramrod link plz
     
  8. TRUCK ACTION

    TRUCK ACTION Grand Toyotaholic

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    Location:
    Vallejo,Ca.
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    I had a post regarding the GM 12SI alternator

    I got a billet cased one from Quality Power with a connector to my Toyota harness, 150 amp output with 100 amps @ idle, was a bet more in cost, but looks & works great!!:cool:
     

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