3G Alternator Upgrade - Remove Old Wires?

Discussion in 'Fox 5.0 Mustang Tech' started by JasinC19, Feb 1, 2012.

  1. While I have the engine out and the wiring is easy to get to, I wanted to get this straight.

    I have this kit installed, including the upgraded larger power wire:

    What I want to know is if I can eliminate the original power wires that run from the starter distribution block to the alternator. They are black with an orange stripe and are taking up space.

    The kit instructions say to just add the new wire, but probably figure most people won't have their harness easily accessible to remove the factory wires.

    I have to imagine the large wire can carry the load no problem.

  2. I did...just a 12v field wire to the alternator, and a 4ga charge wire to the battery side of the solenoid...worked fine on mine for 6+ years...
  3. Here's the correct way to do the 3G wiring. Follow this, save money and it will be done the right way.
    Stangnet 3G install sticky http://www.stangnet.com/mustang-forums/646825-3g-alternator-install-how.html#post6673702

    The old wiring harness contains one yellow/white wire that is the voltage sense wire. It purpose is to measure the voltage drop between the alternator output and the body wiring buss. It will cause the alternator to increase its output voltage if there is a significant drop between the alternator output terminal and the body wiring buss.
    That wire must be present for the alternator to work. For that reason, leave it in place when using a 94-95 Mustang 3G alternator. If your alternator is not a direct one for one swap with a 94-95 Mustang 3G alternator, that may not apply.

    Here's the wiring diagram to show why...


    Do not connect the black orange wires to the alternator: tape them up out of the way. Here is the reasoning behind using only a single 4 gauge fused power feed to the alternator. If you use the two 10 gauge black/orange wires in addition to the 4 gauge wire, you have two fused power feed paths. The total current capacity of the wiring is the sum of the fused paths. The 4 gauge path is fused for 125 amps, and the two 10 gages wires are fused for 60 amps. That is a total of 185 amps, which exceeds the capacity of the alternator. Overload can occur without the fuses blowing, damaging the alternator.

    The worst case scenario is that the alternator develops an internal short to ground resulting in a catastrophic failure. The initial short circuit surge current is limited by the resistance of the wiring. The current in a parallel circuit divides up according to the resistance of the branches. If the 4 gauge fuse opens up first, the two 10 gauge black/orange wires will be carrying the short circuit surge current. Depending on the time lag of the fuse links, they may open up before a fire starts or they may not.
  4. Thanks for the in depth replies guys.

    I am just curious: the PA Performance website says that the alternator I have is 130 amps: 80 amps at idle, 160 amps at 6000 rpm (alternator shaft rpm; Idle is 2000 alternator shaft rpm)

    If I only have the single 4 gauge wire, would the single wire be able to handle the 160 amps max output? I am assuming so, since the fuse is a 200A fuse. See below link for product details:

    I would be overjoyed if I could simplify the equation. Just adding the big wire made me feel... dirty.
  5. Same here.
  6. If your actually PULLING 160 amps from that alternator then it's because something is wrong (battery dead, shorted, etc). You will only pull the amps that the battery and accessories need and not the amps that the alt is capable of producing.

    In other words... If you have so much electronic equipment that you'll be pulling anything NEAR 160 amps continuous, then I might upgrade the wire. Otherwise... the 4 ga. will be plenty.
  7. What happened after 6 years.... lol
  8. Hmm I don't think I will... but if I go electric fan, have A/C running with headlights on, and have 2 aftermarket stereo amplifiers running. Would that do it?
  9. Nope. 4 ga. Is plenty.

    Sent from my HTC Aria
  10. Great. Thanks guys.
  11. Hey thanks for this. So from what I got from this is NOT to remove the orange/black wires. Just don't connect them to the alternator.

    I'll have to go home and check out where this yellow/white wire runs to/from. I was hoping to be able to remove the orange/black wires completely.
  12. You CAN remove them, it's just not necessary.
  13. Wow that wiring kit is pretty cheap. I think its even cheaper than going to Napa and piecing it together yourself haha.
  14. I pulled the engine out in prep for a 4.6 4V...they use different alternators so I can't use my old 3G anymore....otherwise everything was fine.
  15. I just went to a stereo supply store and bought the pieces...I think I only paid like $8...
  16. Really? Napa wants like 6 dollars a foot for the 4 gauge stuff. Then the cost of the fuse holder, fuse and the ring connectors.. I think I payed like around 50 or 60 dollars all together..
  17. The article that Blown88GT posted is saying that the yellow/white wire that works the regulator of the alternator runs into the fused link with the orange/black wires.
  18. +1

    Just another one of those things that I was told could be done cheap, but I ended up losing my ass on haha.
  19. Well the price of copper has skyrocketed lately. Even buying decent sized extension cords is unreal...

    But yeah $60 bucks for something already cut/assembled was a price I was willing to pay