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  1. #1
    Join Date
    Oct 2009
    Location
    New Haven, CT, USA
    Posts
    544

    Default 454 alternator - wiring help

    Has anyone changed there alternator to one w/o the external capacitors? I did a cross reference of the Crusader part # and ordered a new alternator. The body of it is identical but in looking on the Crusader manual, I believe it's a Mando unit where the original might be a Prestolite. It'll bolt up no problem but I'm not sure how to cross over the wiring hook ups. Specifically, the two wires that each have a capacitor and the yellow one with the disconnect. Is the noise suppression built in now and these go away?

    The company that makes the alternator sent me this:

    B+: Battery
    E: Ground
    S: Red wire – battery sense
    EXC: Purple or black – wireignition terminal
    L2: Indicator Light
    P: AC Tap/Tachometer terminal

    Any thoughts appreciated....


    Bob
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    Last edited by bobct; 05-05-2012 at 07:02 AM.

  2. #2
    Join Date
    Aug 2008
    Location
    Fairport, NY
    Posts
    1,472

    Default Re: 454 alternator - wiring help

    Just a first glance, but I see a capacitor on both alternators. It is that black square item with a 250v on it. THe old yellow now is the EXC (excite) going to switched ignition. If you are using battery isolators, then the red sense wire might be better to move. You likely don't need to connect to the tach term. since you are picking up the distributor for the existing tach. It's normally for a diesel that has no distrib.

  3. #3
    Join Date
    Oct 2009
    Location
    New Haven, CT, USA
    Posts
    544

    Default Re: 454 alternator - wiring help

    Dave, I saw that as well. I'm not sure if the eliminates one or both capacitors in the process. Here's what I have so far in trying to cross the two:

    Old yellow= EXC
    Old Orange= B+

    That leaves me with the following wires unaccounted for on the old alternator:

    Blk wire - top right
    Blk wire with big cap - right side
    Blk wire w/small cap - left side
    Red wire - top left

    I don't have battery isolators. Any idea where those would go on the new one?

    thanks
    Bob

  4. #4
    Join Date
    Aug 2008
    Location
    Fairport, NY
    Posts
    1,472

    Default Re: 454 alternator - wiring help

    your old alternator has the voltage regulator and maybe also the brushes mounted on the back of the alternator. Were there more than 2 wires leaving the entire assembly? Namely, battery and excite? I don't know why there would be any more. EXCEPT, I do recommend you use a #6 black wire to run from the case to local/block ground.

  5. #5
    Join Date
    Oct 2009
    Location
    New Haven, CT, USA
    Posts
    544

    Default Re: 454 alternator - wiring help

    I see what you're saying. I'm trying to account for every wire that you see on the old alternator. There are only TWO wires (will double check on the boat), the yellow and the orange. So, yellow should go to EXC, Orange goes to B+ and ignore the rest.

    I know I have a block ground already, is that suffcient since the alternator is bolted to the block? It looks like "E" on the new alternator is a ground. I guess the old alternator used the block mounting as the ground too since I don't see a separate wire.

  6. #6
    Join Date
    Aug 2008
    Location
    Fairport, NY
    Posts
    1,472

    Default Re: 454 alternator - wiring help

    Most installs DON'T have a separate ground/bonding wire. On mine, I had painted the brackets off the engine, and my ground was not great thru the hardware.
    Yes, to your first question. There is a 120 page pdf out there; title: The 12V doctor's alternator book. It has most all about these guys. by Edgar Beyn
    Last edited by diver_dave; 05-09-2012 at 10:04 AM.

  7. #7
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    5,614

    Default Re: 454 alternator - wiring help

    Bob:
    I suggest adding the dedicated ground for the reason Dave gives. It will only take a few extra minutes and it will eliminate a lot of potential issues down the road. I terminated the wire to one of the unused tapped holes in the fromt of the block...can't tell you which one though cause it has been so long.

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