DIY - The OMG I Blew the 140A Alternator Fu$e

LOLSNOW

New member
So it happened. All the leaves were brown and the sky was gray. And while installing my power tray with the fuse box cover off I shorted the line that feeds the alternator into the fuse box and ended up blowing the 140A alternator fuse.

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Now since I was in no mood to fix the issue right away I jammed a nut temporarily so I could drive around... and let's just say DONT do this. The moment you put any significant load while driving you'll 4Runner will start reeking of Japanese hooker bots set to 11. What's even worse is the smell since somehow the fuse box is seems to have a direct line into the HVAC system.

So after pondering whether to do the bypass, goto the dealer, or DIY I ended up with the DIY. Reason being is I didn't like how the bypass would look poking out of the fuse box nor did I think the dealer would take care of my rig with all the electrical stuff I have.

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Over all the whole effort took 1 hour and was relatively easy. Since easy is a relative term I can pretty much guarantee that if you lived your pre-adolescence days without one of these in you Lego set you'll be just fine.



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Now onto the removal. First you'll need to remove this relay box by inserting a tooth pick to release the tab followed up by lifting the box up. Once removing it you'll see a few tabs that lock the lower fuse box to upper fuse box.


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Since the fuse box was clearly designed by the Indian god Vishnu and poor old soul like me doesn't have the luxury of having 4 arms - there was a need to figure out how to unlock the tabs that lock the upper and lower fuse boxes together. What I found out to work the best without damaging the box was tooth picks. You'll need to find every tab to unlock (they're all around the fuse box) and insert a tooth pick to unlock them. There are also a few tiny tabs that you can use a flathead screwdriver while you are working apart the lower and upper fuseboxes.


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Tips:
-I found it easiest to work apart the fuse box from the side closest to the engine with it anchored down with at least one screw
-There's a zip tie holding the positive wire from the battery into the fuse box. Clip this off as it'll give you a lot more room to move the box.
-Near the fender you'll find a wiring harness on the protruding from two sides of the fuse box that are then anchored down to the body with plastic clamps. You can undo these clamps to give you more room.
-On the same wiring harness you will need to remove the electrical tape as the tape actually also holds the two halves of the fuse box together.


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Once you get the two halves separated you get to see this! Since I didn't find much on the internet on where to go from here I'll save you time by saying there's NO WAY you'll be able to remove the alternator fuse from here. Right at this point you're about 60% done but the rest is much easier.


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The pics above will show the location of the fuse block tabs. I found it best jam a bunch of 3/16" flat head screw drivers in while pushing down on the fuse block till it looks like the last picture. Just note that this part requires quite a bit of force because you're working against all the wiring behind it.


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Once you have the block popped out you'll be able to see the bolts holding the fuse in. Carefully remove them on each side and replace the fuse! The rest is pretty much a reversal which is real easy. Just be extra careful when joining the top and bottom fuse boxes back together as the tabs sometimes do not line up too well.
 
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You are correct, 'easy' is a relative term. In my world this would be synonymous with very difficult. Very nice documentation and pics, I will keep track of this one!
 
I think [MENTION=65614]Antman[/MENTION] had a lot more elegant solution. Of course I can't find it at the moment.

Here's a quick link to where he mentions it once, but I know he did a write up on it.
 
I think [MENTION=65614]Antman[/MENTION] had a lot more elegant solution. Of course I can't find it at the moment.

Here's a quick link to where he mentions it once, but I know he did a write up on it.

Hi nglayton,

Here's the thread where [MENTION=65614]Antman[/MENTION] blew his 140A Main Power Fuse. He definitely went about this repair... "THE RIGHT WAY"! I'm posting the link for future folks who need their main fuse replaced, but don't have the time to remove/separate the electrical fusebox... http://www.toyota-4runner.org/2489607-post42.html BTW: "This is an EXCELLENT write-up [MENTION=153545]LOLSNOW[/MENTION] ; seriously good job! 'Best to you',

rig, cheers
 
I think [MENTION=65614]Antman[/MENTION] had a lot more elegant solution. Of course I can't find it at the moment.

Here's a quick link to where he mentions it once, but I know he did a write up on it.

Hi nglayton,

Here's the thread where [MENTION=65614]Antman[/MENTION] blew his 140A Main Power Fuse. He definitely went about this repair... "THE RIGHT WAY"! I'm posting the link for future folks who need their main fuse replaced, but don't have the time to remove/separate the electrical fusebox... http://www.toyota-4runner.org/2489607-post42.html BTW: "This is an EXCELLENT write-up [MENTION=153545]LOLSNOW[/MENTION] ; seriously good job! 'Best to you',

rig, cheers


Glad someone FINALLY got that beast apart. My $7.00/ 15 minute repair is working fine still!
 
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Over all the whole effort took 1 hour and was relatively easy. Since easy is a relative term I can pretty much guarantee that if you lived your pre-adolescence days without one of these in you Lego set you'll be just fine.

This is hilarious! I’ve come very close to blowing mine and I’m pretty sure my day is coming. Great write-up!
 
Would this be the way to replace the cable that goes from battery to fuse box?


Sent from my iPhone using Tapatalk
 
[MENTION=83083]rigtec[/MENTION] [MENTION=65614]Antman[/MENTION]

Thanks! I also referred to your threads when trying to find a solution. Surprisingly there's virtually no guides out there on the internet on how to accomplish this. I hope this helps a few out there where the dealership is not the best option since a majority of those who will have this issue are likely modified rigs.

Would this be the way to replace the cable that goes from battery to fuse box?

Yes. I believe you will have enough room to run a 0awg cable if you so choose. I opted not to since I dont run anything over what's stock to the fuse box amp wise.
 
Glad someone FINALLY got that beast apart. My $7.00/ 15 minute repair is working fine still!

I'm glad to hear it's still working great.

Just curious, do you carry any extra fuses and soldering equipment with you just in case?
 
Recently my GF picked up a 2008 Solara and soon after we noticed the rear defrost indicator would turn on but wouldn't actually do anything. I took my meter to the rear defrost grid, ground on the meter to one side and power probe to the other and no 12v. Looking at diagrams, I convinced myself that the fuse was bad but just not seeing it or the fuse wasn't getting powered up. I figured just simple pull the 40a box fuse out and meter there.

The plastic housing released from the fusebox but the terminals stayed in place!

Dealership has the hardest time finding a replacement. A few orders later a and a couple weeks go by and I finally have a replacement fuse. It's held in with a 10mm bolt on each side internally inside the fusebox. A couple hours later after disassembly and I get the new one in. Still no defrost.
Turned out to be the ground side of the defrost grid had a terminal that was chard and not making good contact.

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Now onto the removal. First you'll need to remove this relay box by inserting a tooth pick to release the tab followed up by lifting the box up. Once removing it you'll see a few tabs that lock the lower fuse box to upper fuse box.

Sorry to bring up this old thread, but I'm having the darndest time trying to get this part of box apart.

[MENTION=153545]LOLSNOW[/MENTION], is there anything else needed to untab in that area? I can't check under that section to see if there's something there that needs to be undone. Also am I supposed to undo the electrical tape on the wiring harness under this part?
 

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Sorry to bring up this old thread, but I'm having the darndest time trying to get this part of box apart.

[MENTION=153545]LOLSNOW[/MENTION], is there anything else needed to untab in that area? I can't check under that section to see if there's something there that needs to be undone. Also am I supposed to undo the electrical tape on the wiring harness under this part?


It looks like you almost have it out but your screwdriver isn't releasing the clip all the way. From what I remember it was a simple matter of releasing the clip and puling up and nothing else needed to be removed for that relay box.
 
So, if this blows.. Would I only need to clip in cold side and hot side wire and tie in a 140 amp inline to them? Seems easy enough and a lot less hassle. Then I can route that and mount it anywhere.
 
So does the stock 140A fuse make replacing the alternator with a more powerful 270A alternator pointless?

Nope, most of us with that have done the "big 3 upgrade" which involves adding heavy gauge wire between:
Alternator Power to Battery Pos (130A fused)
Battery to Body Ground
Engine to Body Ground
If you're working 6 day weeks and don't have time to DIY, any reputable car stereo shop should be able to do this easily. I baffled many a mechanic asking about it, the car audio shop knew exactly what I was talking about.
 

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