3G Alternator Install: A How To

Discussion in 'Fox 5.0 Mustang Tech' started by Roland69, Jul 4, 2006.


  1. Mark Cappello

    Mark Cappello New Member

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    Apologize for the lack of knowledge here.

    Does the green/red wire going to the regulator act like a relay? the green wire doesn't pass along the current from the yellow wire over to the black white wire does it? I thought the yellow wire provided the power to the regulator? so if that provides power to the regulator, what does the green/red do exactly? why is it called an excite wire? does the white black wire feed power to the regulator or does it feed power to the stator windings?

    What i can't tell from the diagrams is the direction or flow of electricity. I'm assuming the black orange FEED power to the battery when the engine is running, but the black orange wire has power available from the battery when the engine is off..correct? Your alternator testing procedures have you check those black orange wires for 12 volts when the engine is off and when the ignition is off. And the fusible link in that circuit is to protect the battery from over charging from the alternator?

    The yellow sense wire, also has power from the battery when engine off and ignition is off, but when the engine is running, its detects voltage drop and tells the regulator to increase or decrease the voltage or amps going to the battery. the fuse in the yellow wire circuit is there to protect the alternator batt feed wires from blowing out the regulator?
  2. Mark Cappello

    Mark Cappello New Member

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    I finished the 3g alt upgrade today. thanks everyone for all your input
  3. Dctaylor

    Dctaylor New Member

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    I'm in desperate need of help. I ordered a 200 amp alternator to replace my current 200 amp alternator that was already on the car when I purchased it. The new alternator has the green wire removed from the plug and the yellow wire is run to the where the power wire goes . The white wire jumps off of the plug and into the plug on on the side of the alternator . Per rareelectric.com all I am supposed to do is connect the power wire to the terminal and because it is a one wire alternator. Is this correct? Also I will have to upgrade from the 4 gauge to the size you stated. My ground wire is the belt style hooked to the firewall is this the wire I need to upgrade as well?
  4. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    I am not familiar with the alternator you specified. You will need to contact the people that sold/manufactured the alternator.

    I also have no way of knowing how much current the ground wire you described is capable of handling.

    The secondary power ground is between the back of the intake manifold and the driver's side firewall. It is often missing or loose. It supplies ground for the alternator, A/C compressor clutch and other electrical accessories such as the gauges. The clue to a bad ground here is that the temp gauge goes up as you add electrical load such as heater, lights and A/C.

    Any car that has a 3G or high output current alternator needs a minimum of a 4 gauge ground wire running from the block to the chassis ground where the battery pigtail ground connects. The 3G has a 130 amp capacity, so you wire the power side with 4 gauge wire. It stands to reason that the ground side handles just as much current, so it needs to be 4 gauge too.

    A 200 amp alternator will need a cable larger than 4 gauge for both power and ground.

    Wire size current table:
    [​IMG]
    Dctaylor likes this.
  5. Dctaylor

    Dctaylor New Member

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    Thanks. I'm I will have those wires upgraded then do the install the way they specified. Which will have me leaving the current pig tail free and connecting the power wire to the back of the alternator. Which I don't see how that is going to send the charging level to the dash gauge.
    Thanks for your quick response.

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