good alternator wont hold charge..zc swap

Discussion in 'General Motoring' started by ZCjason, Dec 2, 2004.

  1. ZCjason

    ZCjason Guest

    hey does anyone know why my alternator will not hold a charge..i have bench
    tested it and it test good. there is a little 2wire plug near the
    alternator, would that have anything to do with it??? oooh yea this is
    in a ef civic 4d.
    ZCjason, Dec 2, 2004
  2. ZCjason

    Randolph Guest

    I am not sure what you mean by the alternator not holding a charge,
    (batteries are supposed to hold a charge, alternator are not). Can you
    describe the symptoms in a little more detail? Also, you didn't mention
    what year the car is.

    When you turn on the ignition (without starting the car) does the
    alternator light turn on? If it does not, you have a problem, and
    probably won't get power from the alternator.

    What wires did you connect at the alternator? The most primitive of
    alternators need 3 connections: Ground (usually through the mounting
    bolts), Output (fat wire) and the wire to the ignition switch. Without
    the latter, the field winding will not get energized, and the alternator
    will not deliver power. Newer (read: not ancient) cars have a few more
    connections, like a power-good signal to the ECU and a "reduce voltage"
    command from the ECU.
    Randolph, Dec 2, 2004
  3. ZCjason

    remcow Guest

    I am assuming you mean that the battery won't hold a change after you've
    replaced your alternator.

    Make sure you see about 14V or so with the engine running on the battery. If
    you see that, the alternator is charging which is basically what an
    alternator is for. If you don't see 14V, make sure you check your battery
    wires to the alternator and ground.

    Also, make sure that you don't have a current drain somewhere -- something
    is on when it should be off with the car off.
    If you have an amp (or current) meter that can measure amps, pull the
    battery off and put a meter in series with the positive lead.
    Don't(!) start the car or open doors.
    The current going through should be minimal (in the order of milliAmps)
    because all it is feeding without the keys in the ignition is your clock,
    storage backup for ecm/radio and alarm -- all requiring very little power.

    Hope you find it soon.
    remcow, Dec 2, 2004
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