What are the 3 OEM Power Wires Running to the Battery??

Discussion in 'Electrical' started by MrNyceCream, May 15, 2019.

  1. MrNyceCream

    MrNyceCream Member

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    If this has been asked before, please let me know where the thread is. I've tried searching for the past three days.

    Here it goes. I recently did a big 3 wire upgrade (Alternator, bat to block ground, block to chassis ground, 0awg) on my 07 Expy. I noticed that all the power wires were in terrible condition, not just the alt to bat wire. I was able to identify 2 of the 3 wires and get those replaced.

    1st replaced wire: 0awg from the alternator to battery
    2nd replaced wire: 4awg from starter to battery
    3rd wire:?? I have no clue but it looks like 6awg

    I really want to replace the 3rd wire as it is corroding from the inside. This wire is also extremely short and wired like a cable, not fine strands like normal power wire. I thought it might be the starter wire because of the corrosion mentioned in other threads, however, the starter wire was pretty bad too but that wire is new and ready to roll.

    Any help would be greatly appreciated. If needed, I can post some pictures. Thank you for your time.
     
  2. stamp11127

    stamp11127 Super Moderator Staff Member

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    Might be the lead to the fuse box. Follow it and you will know where it ends. I'm pretty sure Ford didn't use solid core wire anywhere on the vehicle.
     
  3. MrNyceCream

    MrNyceCream Member

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    I forgot about the power wire to the fuse box. I replaced that with 4wg. Stamp, do you think it might be something installed by the previous owner? It's almost impossible to trace as it disappears under the battery shelf
     
  4. GAIN-MOB

    GAIN-MOB Super Moderator Staff Member Supporting Member

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    Pics

    Sent from my SM-G965U1 using Tapatalk
     
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  5. MrNyceCream

    MrNyceCream Member

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    Figured it out. 4 total wires

    1. Power to the alternator
    2. Power to fuse box above the radiator
    3. Power to the starter
    4. Power to Battery Junction box

    Looks like someone replaced the 4th wire with a solid core wire at one point.
     
  6. Munkiebunz3

    Munkiebunz3 Full Access Members

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    Thanks for the leg work on this. I'm planning on doing the same thing due to corrosion.
     
  7. Trainmaster

    Trainmaster Old School Member

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    Solid wire is not a good choice for automotive work which is why manufacturers don't use it. Vibration and flexing causes fatigue and failure.
     
  8. MrSticker

    MrSticker Full Access Members

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    Got this from a 2003 wiring diagram

    power.jpg
    ground.jpg

    on my 2003XLT
    I see 3 wires (cables) coming off the POSITIVE battery post
    - alternator (they call it a GENERATOR which it ain't)
    - starter (or starter circuit/solenoid/relay/?, I don t actually know whats in that circuit)
    - fuse box
    and 2 wires (cables) coming off the NEGATIVE battery post
    - starter circuit
    - firewall

    its odd that the total amount of copper conductor connected to POSITIVE and NEGATIVE battery posts are not equal. I would have thought they would be same cross sectional area. Why is this?

    I would have thought more connection from battery to common frame ground
    but I guess that probably inherent with starter motor?
     
    Last edited: Jun 7, 2019

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