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Old 12-04-2018, 12:22 PM
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New Engine blowing main fuse (80A)

I installed a new engine in my truck(see signature). I got everything hooked up and applied power, immediately blew the 80a fuse in the fender fuse box.
No crank, no start, the only lights that work were headlights.
I checked every ground I can find, all tight, shiny, metal to metal.
Starter and alternator are connected correctly.
The alternator was upgraded to an 140 amp unit, connected using stock wiring.
I didn't replace any cables connecting battery to starter, although it does have a funky spade connector that the DAPO installed as a( I assume)
theft prevention measure.
I am on my way out to find a replacement fuse.
I am comfortable using a Multi meter and have the correct FSM.
I did a search and it would appear that my problem is a Short to ground?
That is why I started with the starter and alternator, thinking that I may have connected something wrong, had bad wiring, metal to metal tec, but an initial visual search did not reveal anything burnt,or melted.
So,
any thought or direction would be much appreciated. I will post some pictures this afternoon.
Thanks in advance!
John
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Old 12-04-2018, 03:12 PM
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After you replace 80Amp FL, and before you connect to battery, measure resistance between ground and the wire that goes to fuse block. That's the wire thinner than the one that screws to starter solenoid stud terminal.
Let us know what u see.
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Old 12-04-2018, 05:46 PM
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Thanks Rad,
I will get back on it in the am, let you know what I find.
The guys at 22re performance also suggested I recheck alternator connection and visually inspect where the wiring harness enters the cab.
Thanks again
Edit: That wire is cut and has the spade connector installed. I drove the truck for about 8 mos like that with no problems, but you never know.
I noticed the white wire coming out of the fuse block is a different gauge than the on it connects to.
One of the reasons I bought the truck was the lack of hacked wire.
Oh well, an opportunity to learn.

Last edited by Republic77; 12-04-2018 at 05:52 PM.
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Old 12-04-2018, 09:36 PM
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Originally Posted by Republic77 View Post
Thanks Rad,
...recheck alternator connection ...
Another thing to check. Disconnect everything from stud terminal of alternator. With alternator installed normally, measure resistance of stud terminal to ground. You should get LOTS of mega-ohms (sorry forgot what mine read but, IIRC it was like 33 Meg-ohms. If you get low reading, you may have a bad rectifier diode.

Edit: That wire is cut and has the spade connector installed.
Sorry... what wire? A picture paints a thousand words.

I noticed the white wire coming out of the fuse block is a different gauge than the on it connects to.
The FL that looks like a fuse is the FL AM1.
The wire between battery positive and fuse block is the MAIN Fusible in schematic. Make sure it is intact and DO NOT REPLACE WITH THICKER WIRE.

It should look like this.



It is attached to a plate that screws on bottom of fuse block to the terminals of the 80-Amp FL module. Terry's87 has details how to disassemble.

If you want to fully utilize your 140-Amp alternator capacity, do as Chefyota4x4, Redeth, and I did like this , and supply all added circuits from a fused distribution block directly from the battery. This way your alternator and battery will directly work hand-in-hand, supply the higher current directly to your added circuits without passing through the stock fuses and FL's, AND stock fuse and fusible links will protect stock circuits - critical to truck operation - no matter what happens to added circuits.


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Old 12-04-2018, 10:17 PM
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Rad,
Thanks, I will get pictures up in the morning, I realize that describing a problem on the internet is a poor
substitute for a visual representation of the problem.

You have given some great advice, which is greatly appreciated, and I will get those images up tomorrow.
I have the 80amp FL module pulled out of the fuse box after reading Terrys87 description.
Thanks,
John
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Old 12-05-2018, 12:19 PM
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This is the set up currently

Top of FL

spade connector FL side

spade connector starter side
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Old 12-05-2018, 12:25 PM
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Here are a couple more. Looking at this it is apparent it needs to be fixed, so I am know thinking all new ground battery cable and new starter cable with new FL.

tape removed

gratuitous engine shot
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Old 12-05-2018, 02:34 PM
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Not able to source the fuse part that the FL screws to, so no resistance reading on that yet.
I got lots of resistance from stud terminal on ALT to ground, can rule that out.
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Old 12-05-2018, 02:38 PM
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found-

This has low resistance,so clean up, replace heat shrink and cut off spade and add ring terminal? Edit: This appears to be 6 ga wire?

Last edited by Republic77; 12-05-2018 at 04:11 PM. Reason: found item
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Old 12-05-2018, 04:12 PM
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Originally Posted by Republic77 View Post
...

This has low resistance,so clean up, replace heat shrink and cut off spade and add ring terminal?
Too short, it likely blew/burnt-out which is someone tried what you have now. Just order a new one, or replace the whole length with white fusible link wire.
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Old 12-05-2018, 05:55 PM
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Rad4Runner:::: Do you by chance know the part number of the MAIN fuseable link wire and plate unit????
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Old 12-05-2018, 09:05 PM
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Originally Posted by millball View Post
Rad4Runner:::: Do you by chance know the part number of the MAIN fuseable link wire and plate unit????
Repair wire is, 82991-.....
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Old 12-05-2018, 09:37 PM
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Originally Posted by millball View Post
Rad4Runner:::: Do you by chance know the part number of the MAIN fuseable link wire and plate unit????
Sorry, I've never looked for it. Would definitely be nice if someone could chime in.

Originally Posted by Co_94_PU View Post
Too short, it likely blew/burnt-out which is someone tried what you have now. Just order a new one, or replace the whole length with white fusible link wire.
This^^^

Republic77,
if you could not find OEM replacement, find out what gauge that factory white wire connected to the plate (i.e., measure diameter), find fusible link wire 4 gauges thinner, then spice to that white wire or replacement, terminate one end of FL wire with ring terminal to connect to battery connector.

I'd also replace that POS ( for positive and for you know what - LOL) battery cable. What's that silver metal thing on other end? That could short to ground.
Recommend using "Marine Battery Terminals. Robust, easily-available, versatile.


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Old 12-06-2018, 08:07 AM
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Hey Rad, I am going over to the dealer to see about a OEM replacement for the FL, I will get relevant part numbers and post.
The white wire exiting the plate on the FL is 39 strand/.4 mm copper, I had it worked out to be 6 gauge. Thoughts?
You are saying find a FL wire 4 ga. thinner (10 ga) and splice into the existing fl IF I cant find oem, right?
Yeah that cable is definitely a POS, the metal part you referenced is actually a threaded stud half way down the length I have no idea what it is for, but I am getting rid of it.
Thanks for the tip on Marine batt terminals, I will grab a couple today.
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Old 12-06-2018, 08:41 AM
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Originally Posted by Republic77 View Post
Hey Rad, I am going over to the dealer to see about a OEM replacement for the FL, I will get relevant part numbers and post.
The white wire exiting the plate on the FL is 39 strand/.4 mm copper, I had it worked out to be 6 gauge. Thoughts?
You are saying find a FL wire 4 ga. thinner (10 ga) and splice into the existing fl IF I cant find oem, right?
Yeah that cable is definitely a POS, the metal part you referenced is actually a threaded stud half way down the length I have no idea what it is for, but I am getting rid of it.
Thanks for the tip on Marine batt terminals, I will grab a couple today.
Have another look the photo he posted. I think he misspoke and I certainly did.. Note the none fusible link wire at the battery end, this is larger than the FL wire guage by one or two sizes. This wire attaches with a crimp to the FL wire, it should be a bit shorter than the battery is tall. The White FL wire (rating I think is 100-120 amps, there are some good posts that cover this) makes up the rest of the length. It crimps to the large plate at the end. This whole wire run should be covered in a noncombustable sheeth (fiberglass weave) and have the normal sheeth over this to keep it clean and dry.


Or just buy one from Toyota, 82991 (from memory) is the base part number.
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Old 12-06-2018, 08:51 AM
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Originally Posted by Co_94_PU View Post
Have another look the photo he posted. I think he misspoke and I certainly did.. Note the none fusible link wire at the battery end, this is larger than the FL wire guage by one or two sizes. This wire attaches with a crimp to the FL wire, it should be a bit shorter than the battery is tall. The White FL wire (rating I think is 100-120 amps, there are some good posts that cover this) makes up the rest of the length. It crimps to the large plate at the end. This whole wire run should be covered in a noncombustable sheeth (fiberglass weave) and have the normal sheeth over this to keep it clean and dry.


Or just buy one from Toyota, 82991 (from memory) is the base part number.
Thanks CO,
I am going out the door to the stealership right now, I would prefer oem to a splice of my own making, but if it comes down to it...
In the picture, of my FL, the wire that exits the plate is*I believe* 6 gauge, I will get a 10ga FL wire to splice into the end of the existing short run I have
and solder a ring terminal to connect to battery pos (+).
Thanks for the part number,I will confirm later.
John
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Old 12-06-2018, 09:52 AM
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Update: 82991 is the number for the replacement wire. Good memory CO!
It is, unfortunately, NLA from the dealer.
So I will get some clarification on the FL wire configuration,then use my original plate and make one.
Got the marine terminals and a new run of 4 ga. wire for my (+) wire.
Thanks for the help!
Edit
Is there any reason the (-) ground wire cannot be increased in gauge?
I bought a ready made deal with the intention of lopping of the battery terminal and replacing, it is a larger diameter
than the stock wire tho. I could easily do the same with the old wire, it ohms out fine.
Thoughts?

Last edited by Republic77; 12-06-2018 at 10:16 AM. Reason: Add question
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Old 12-06-2018, 10:26 AM
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Very good to upsize wires if feasible.
Very Not good to upsize fuses or FLs
Haven't tracked down if you have a dead-short to ground?

Last edited by RAD4Runner; 12-06-2018 at 10:28 AM.
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Old 12-06-2018, 10:38 AM
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Originally Posted by Republic77 View Post
Not able to source the fuse part that the FL screws to, so no resistance reading on that yet.
I got lots of resistance from stud terminal on ALT to ground, can rule that out.
This is where I am at in the process.
After I sort out the wiring,I will have a better baseline to test. Eliminating that (+) wire with that funky metal part will
reduce possible causes by one.
Copy on that" very not good upsize" comment.

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Old 12-07-2018, 04:01 AM
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Originally Posted by Republic77 View Post
This is where I am at in the process.
After I sort out the wiring,I will have a better baseline to test. Eliminating that (+) wire with that funky metal part will
reduce possible causes by one.
Copy on that" very not good upsize" comment.
This was something I meant to mention in that last post, I guess I overlooked it or wasn't particularly clear. I was in a bit of a hurry.

The standard wire should be larger than the fusible link wire.
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