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Alternator Fuse and Fuse Box-Battery Wire Replacement/Upgrade

Discussion in '2nd Gen. Tacomas (2005-2015)' started by Chuy, Mar 6, 2016.

  1. Mar 6, 2016 at 11:58 PM
    #1
    Chuy

    Chuy [OP] Well-Known Member

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    Here are some photos and tips to removing the fuse and replacing the fuse box-battery wire. I have a V6 auto 07 Taco; your box may differ but similar principles should apply.

    I took apart the fuse box to replace the fuse box-battery wire and took out the fuse to see how it's done in case I ever have to replace it. Didn't find a how-to; so I posted this for future reference. I had wanted to replace the OEM fuse with a 200 amp fuse but I couldn't find one (prepping for a future alternator upgrade). The one in my truck appears to be the max they make, a 140 amp fuse. I'll be running a fused jump wire - alt to relay to battery once I get my 2nd battery installed.

    1. Remove battery; remove fuse box cover; open wire harness connectors on fender wall - the two closest to fuse box. Also consider clipping the zip tie on bottom of fuse box. Both will give you more leeway to install the fuse box tray later on.

    2. Remove nut (12mm) holding alternator-fuse box wire, and disconnect the three harnesses.

    3. Use pliers to pull out the small plastic cover covering the cable and harness wiring. Push wiring out of the way.


    4. Use small screwdrivers (or awls or single strand wiring) to hold open the six tabs (red arrows) that clip the fuse box tray/panel to the fuse box. Use pliers to gently pull up the tray (at blue arrows). It will slide on grooves straight up; don't pull on the tray until the tray clears the grooves or you may damage the thin grooves. I found it easiest to work your way from left to right.


    5. Remove bolt holding one of two fuse hold down bolts (M6 bolt with 10mm head). Lower bolt/wire goes to battery. Your wire will be a 5 gauge black wire; I upgraded mine to 2 gauge: 14.5 inches long; 6mm (1/4") lug on fuse box end; 8 or 10 mm (5/16" or 3/8" depending on your terminals) on the battery end.


    6. Remove this wire harness 'socket'. It has four tabs and is a bit tricky to pull out. It will take some wiggling as it is connected to another socket. Tabs are not inside the three holes; they are low and outside the three holes.


    Harness socket removed. You can now access the other fuse hold down bolt. That's the AC fuse bolt next door.


    7. Voila. Now, put it all back together!


    8. You may have to enlarge the hole a bit where alt-battery wire exits the fuse box to fit the larger gauge wire. I went a bit overboard. Use new zip tie to hold wire in place.



    Here is a side comparison of the OEM fuse box to battery wire and replacement upgrade wire.



    Here is a cross section of the wires, comparing 2 gauge, 4 gauge, and the OEM 5 gauge. I call it 5 gauge because it measures 4.8mm; close to 4 gauge (5.2mm) - call it 4.5 gauge.



    My thoughts on replacing the fuse box-battery wire, and I can be completely wrong on this: The theoretical amperage limit of a 5 gauge wire is about 90 amps. The fuse is 140 amps. It's possible, then, that the 5 gauge wire will heat up and possibly catch on fire before the fuse blows. Those of you without the 130 amp alternator will not have to worry as much. I'd rather play it safe. The alternator to fuse box wire is 4 gauge; so, this short fuse box to battery wire is the weak link - not any more ...
     
    Last edited: Mar 7, 2016
    Mudman, po35042, truchador and 7 others like this.
  2. Mar 7, 2016 at 12:13 AM
    #2
    Nirvana

    Nirvana Tesla Auto

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    Nice work, very thorough write up.
     
  3. Mar 7, 2016 at 12:36 AM
    #3
    Jimmyh

    Jimmyh Well-Known Member

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    Good job, but I think your worries are unfounded.

    The factory copper appears to be the same cross section of the wire ( not the insulation ) as the 4 gauge wire in your picture. Barring a loose connection I can't see this wire burning up or catching fire....
     
    06Tacooo and 12TRDTacoma like this.
  4. Mar 7, 2016 at 12:39 AM
    #4
    12TRDTacoma

    12TRDTacoma Ocean TRD

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    Huh... I may do this tomorrow just for some extra peace of mind. I have tons of 1/0 guage cabling leftover from spare projects. This should work out just fine. :)
     
    Athlaos likes this.
  5. Mar 7, 2016 at 12:41 AM
    #5
    Chuy

    Chuy [OP] Well-Known Member

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    Wires looks similar but I measured a difference with digital calipers: 4.8mm for OEM and 5.2mm for the 4 gauge. If I wasn't doing some other wire upgrades for preparation of a 2nd battery install and future alternator upgrade, I would not have noticed the different gauge wires used.
     
    Last edited: Mar 7, 2016
  6. Mar 7, 2016 at 12:46 AM
    #6
    Chuy

    Chuy [OP] Well-Known Member

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    Caught a mistake in #5, bolt is M6, not 10mm. The head uses 10mm socket, is what I was trying to say. Fixed.
     
    Crom likes this.
  7. Jul 31, 2017 at 7:12 PM
    #7
    StOrMyThEtAcO

    StOrMyThEtAcO @stormythetaco

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    Just did this today! Thanks for the write up! It was perfectly executed and easy to understand.
    image.jpg
     
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  8. Aug 27, 2017 at 9:41 PM
    #8
    HandOfGod

    HandOfGod Well-Known Member

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    My wire is also too short for my Northstar 31m so thanks for the write up. Surprisingly hard to get a replacement wire. My soldering skills sucks and I don't own a good crimper so thank goodness for online!
     
  9. Aug 28, 2017 at 12:54 AM
    #9
    Chuy

    Chuy [OP] Well-Known Member

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  10. Aug 28, 2017 at 7:22 AM
    #10
    HandOfGod

    HandOfGod Well-Known Member

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  11. Aug 28, 2017 at 7:31 AM
    #11
    EatSleepTacos

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  12. Oct 17, 2017 at 7:42 PM
    #12
    arwinnnsd

    arwinnnsd Rockin the Death Train!!!

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    Chuy:
    Thank you for the right up! Was most helpful.
     
  13. Oct 17, 2017 at 10:43 PM
    #13
    Chuy

    Chuy [OP] Well-Known Member

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    @arwinnnsd You are welcome. Did you lengthen the battery cable? I would like to add an estimate length for those with center terminal batteries, ie NorthStar batteries.
     
  14. Oct 18, 2017 at 9:03 AM
    #14
    arwinnnsd

    arwinnnsd Rockin the Death Train!!!

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    Yeah, I went with a 2 gauge x 18"; just installed it yesterday, seems a bit long. But I'm getting my x2power (similar to the northstar) group 31 battery tomorrow and hope to install it Friday, so we'll see how that works out.
     
  15. Oct 22, 2017 at 12:09 PM
    #15
    MonkeyProof

    MonkeyProof Power Top

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    I used zipties instead of wire to hold the tabs in place, found the zipties easier to work with.
     
  16. Nov 23, 2017 at 5:38 PM
    #16
    HandOfGod

    HandOfGod Well-Known Member

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    Here is the Camco 18” 2 gauge wire from Amazon compared to the stock wire.4823130B-19FD-4820-B1C6-5893FB1BAE79.jpg
     
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  17. Jan 15, 2018 at 11:02 AM
    #17
    CODOTUS

    CODOTUS I know how to get places

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    Thanks for the write up! Blew my ALT fuse yesterday and need to replace. This was the only write up I could find on this without actually breaking the fuse box. Much appreciated!

    Going to tackle this once this snow storm passes.
     
  18. Jan 16, 2018 at 11:25 AM
    #18
    CODOTUS

    CODOTUS I know how to get places

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    Just a heads up to anybody only needing to replace the ALT fuse and not doing the cable upgrade. I just had to lift the fuse box up on the left side and I was able to get to the ALT fuse bolts. I also didn't need to disconnect the two wiring harnesses going to the fuse box from the side of the engine bay.

    Took me about 20 mins to do the ALT Fuse. Cheers!
     
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  19. Jan 16, 2018 at 12:57 PM
    #19
    Chuy

    Chuy [OP] Well-Known Member

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    @CODOTUS The fuse has two bolts. I can you removing the one facing outside the box, but how did you access the bolt facing the inside?
     
  20. Jan 16, 2018 at 1:02 PM
    #20
    CODOTUS

    CODOTUS I know how to get places

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    Took the female plug out in your 4th image. Just raised the left side of the fuse box up and got the 2nd bolt.
     

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