Why is my in-line fuse blowing !?

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Side note, can be handy to keep a few lengths of wire with jumper clips on each end in the toolbag - pretty easy to jumper the coil (and the started) and bypass all the factory wiring to get it running and off the side of the road.

Similar to the bad starter thread and push starting...can be handy to get it going again, they're simple rigs.

right that's exactly what my uncle said - just bypass everything for now...me, being me (too much of a perfectionist) wanted to figure out exactly what's going on...

Did you inspect the back of fuse block yet ?

s*** I didn't, my day got out of hand quickly and I didn't even spend any time on the car, I feel bad because you told me too so that's gunna be the first thing I do in the morning and report back. s*** I might run out with a flashlight right now to give it a gander
 
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Lets start a betting pool...

Who's got bad alternator / regulator?

Who's got short on the back of the fuse block?

Who's got gremlins in the dash?

:popcorn:
 
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30amp fuse in the in-line and boom fired fine. definitely ran rough though not like it was the day previously ..I had only taken it up to a 25a before saying how much more do I go before I screw something up ... but I should have just hit it with the 30amper...

so ill wait for my fusible link and install that - hopefully that was it...I mean I have nothing...
how much amp does the fusible-link hold?

I just don't know how it could run fine for days and days with a 15amper without a problem, and then all the sudden work only with a 30amp which is double ... I'm just confused as to how that could just happen.
 
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Not sure offhand what Uncle Toyota used, but likely at least 60a for the fusible. Heater fuse is 20, headlights are 20, engine is 15...etc
 
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Not sure offhand what Uncle Toyota used, but likely at least 60a for the fusible. Heater fuse is 20, headlights are 20, engine is 15...etc
Right … so it’s just basically covering the fuse box added up.
How the hell was the car firing so easily and well with just 15a covering all that. You would think it would blow automatically everytime.
 

pb4ugo

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So, shouldn't the fusible link or fuse be determined by the alt output? I think the problem with using a fuse is that when the amps exceed it capabilities the fuse blows immediately, and a fusible link can handle the spike for a short time b4 blowing. You can buy link wire at any auto parts store and make your own link . It is different than regular wire. It needs to be the proper size link by guage and length. Then see if your issues still exists.
 
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So, shouldn't the fusible link or fuse be determined by the alt output? I think the problem with using a fuse is that when the amps exceed it capabilities the fuse blows immediately, and a fusible link can handle the spike for a short time b4 blowing. You can buy link wire at any auto parts store and make your own link . It is different than regular wire. It needs to be the proper size link by guage and length. Then see if your issues still exists.
awesome best, most simplest answer .... much appreciated ... while I wait for my OEM spec one from Coolerman...
 
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You do not need a fuse to cover the entirety of the fuse block unless you intend to have everything ON, head lights, brake lights, tail lights, heater blower, radio, AMP, dash lights, turn signals, etc, when you fire it up. I run a 30a fusible link from Oreilly's and it works fine. You have a lot of good advise here that you can work with and if I were you, I would list all the suggestions and programmatically work through them. Cheap and easy...put the small fuse back in, pull all fuses at the block on one end except the engine. Fire it up. No BLOW, connect a fuse at a time fully and try again until you blow something. Running rough due to electrical sounds like you may have a bad alternator or voltage reg like mentioned above.
Best of luck!
 
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Was on mobile eariler, so was short-worded...definitely don't need to cover the whole fusebox, but it doesn't take much to use most of it on these simple rigs. If you have the front and rear heater, the fans draw a surprising amount of their 20A circuit...same for the headlamps. If you're going for a drive on a chilly night, that will use quite a bit...headlights (prob 15A out of 20 rated), heater (15A out of 20 rated), markers/tails/dash (5-10A?), dash gauges, and ignition (5A?).

Fusible link will handle the varying load better of course, but that's still a decent amount of constant load.
 
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my volt regulator is literally brand new so that's not the problem & my wiring is perfect - checked yet again to quadruple check al wires were correct (check) - So, based on recommendations I need to check my alternator.. I'm gunna take it off and take it to orielly's or Napa and have them bench it...because that was one of the first things I replaced when I got the rig and the guy helping me at the desk I could tell just grabbed whatever the computer told him and it probably wasn't correct ( I know at the minimum th fully is way to thin for the size belt fj's call for..so there's one issue with it... My rig came originally with a OEM alternator, but since the lines were crossed on the ride home from purchase (2hr ride) I figured it was shot, but I think I'll have them bench that one too just in case it was fine all along ... here's a pic the original one

IMG_2343.jpeg


IMG_2344.jpeg


IMG_2345.jpeg
 
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Was on mobile eariler, so was short-worded...definitely don't need to cover the whole fusebox, but it doesn't take much to use most of it on these simple rigs. If you have the front and rear heater, the fans draw a surprising amount of their 20A circuit...same for the headlamps. If you're going for a drive on a chilly night, that will use quite a bit...headlights (prob 15A out of 20 rated), heater (15A out of 20 rated), markers/tails/dash (5-10A?), dash gauges, and ignition (5A?).

Fusible link will handle the varying load better of course, but that's still a decent amount of constant load.


right I agree...I think I need 1/o gauge cable and c=to check my alternator and add the fusible link and then see if that corrects anything
 
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Just unplug it first and test before taking it all the way off. Could just be wiring...you mentioned lines were crossed originally. That's what was blowing my engine fuse and it wasn't charging the battery. Alternator is still good after it was fixed
 
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Just unplug it first and test before taking it all the way off. Could just be wiring...you mentioned lines were crossed originally. That's what was blowing my engine fuse and it wasn't charging the battery. Alternator is still good after it was fixed

got it ... I have my Hongda out ready to go but what do I do disconnect wires and then check what Ohms? and which terminals do I check for ...sorry for questions im so novice electrically. im going to open my Haynes and my @F engine manual and see what it says - probably explains everything I just asked. But ya when you say test it I dont know what to test and how to read the readings of the test..continuity is easy tone or no tone...ohms a little more complicated but that's just dialing it in. but ya im kinda a lost dog when it comes to this. IM LEARNING though!!! I fricken re-wired that nastyness the previous owner left me with.

and no wonder he won't pick up his phone to talk to me me because he sold it to me knowing I was f***ed for smog, CA yo legally have to present last smog and he never did but I didn't ask so that's on me. but ya wish the f***er would answer just so I could ask some questions...
 
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Fuses are there to protect the wiring, not the components. So whatever gauge wire the fusible link is on, the rating should be less than that. It's there to be the weak link in the electrical system.

Continuity and Ohms are basically the same function. Continuity is just an go/no go version of ohm reading. Anything less than about an 1 ohm is essentially a short (i.e. connected). If you see an "OL" then it's open circuit (not connected). For this type of troubleshooting you can use continuity or set the ohms reading to the highest level, you area essentially just using it as a continuity meter.

Remove your inline fuse, put one lead into the fuse socket on the wiring side. One side of the fuse holder is connected to the battery, you want the side that's connected to the rest of the wiring. Connect the other lead to ground, either the battery negative post or a ground point. Luckily, most everything metal in the engine compartment of an FJ40 is grounded, so you could just find any bolt. You should be reading open circuit, or "OL" on your meter, or no tone. If you do hear a tone or see a closed circuit, it means something is shorting to ground and that's why your blowing fuses. So turn on the ignition and start unplugging things until the tone stops.

Also, if you try and turn the ignition to "start", the starter motor windings are essentially a giant short to ground, so don't worry about that.
 
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got it ... I have my Hongda out ready to go but what do I do disconnect wires and then check what Ohms? and which terminals do I check for ...sorry for questions im so novice electrically. im going to open my Haynes and my @F engine manual and see what it says - probably explains everything I just asked. But ya when you say test it I dont know what to test and how to read the readings of the test..continuity is easy tone or no tone...ohms a little more complicated but that's just dialing it in. but ya im kinda a lost dog when it comes to this. IM LEARNING though!!! I fricken re-wired that nastyness the previous owner left me with.

and no wonder he won't pick up his phone to talk to me me because he sold it to me knowing I was f***ed for smog, CA yo legally have to present last smog and he never did but I didn't ask so that's on me. but ya wish the f***er would answer just so I could ask some questions...


Sorry I'm saying just unplug the alternator and try to start it to see what happens with the fuse
 
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so while Mr. Baker is putting together my fusible link....I was at the auto shop and saw fusible link and had not description just 3 different sizes of wire. I went with he highest because it matched the AWG on the main white power line it would be connected to. [brought out my box of recycled lengths of OEM wires - (Gold by the way)] ..should I just make some terminals up and plug it and attach? it didn't say what it was rated AMP-wised, again you could only choose between different Gauges. so that confused me so anyways just wondering if I should even mess with that or leave my in-line packed with a 30amp and have a 40a on hand just in case while I wait for the pro Mark to get mine all together? I think I answered my own question.
IMG_2348D.jpeg


IMG_2349D.jpeg
 
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what Gauge does everyone use for their battery cables ?
I was thinking of making up 1AWG cables instead of 2awg because of the winch, arb, tach, dual tank, flood lights, etc.
thoughts on that?
 
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What is your alternator output connected to?
What is connected to your battery?

When I bought mine, there was a 30 amp breaker (blow and automatically reset) between the battery and the white wire out of the harness. Following the diagrams I can find (haynes) that wire goes to the ampmeter and then the alternator, and somewhere it connects to the fuse block (still trying to figure that out?).
Anyways, preparing to upgrade the alternator (corolla 60 amp, not much but easy fit) I ran a heavier wire direct from the alternator output to the battery. (ampmeter never worked to begin with, and white wire on each side spliced together).

in short, previously with more original wiring, alternator was on the far side of that breaker from the battery. Now, battery and alternator are on the same side of that breaker.

And now that breaker blows all the time. It's 30 amps. 60 watt headlights at 12 volts are 6 amp each? heater fan and windshield are probably close to 10 amps each. Add in all the tail lights and marker bulbs and a few gauges, it's well over 30 amps if all that's on at once (which is should be at night in light rain or mist). And I blow that breaker even without the heater or wipers on sometimes.

Prior to my misadventure in wiring, all the power for these lights and accessories came from the alternator and were only protected by the fuse in the fuse panel. Now, power from the alternator comes through that 30 amp breaker, and it's not big enough.

and my current issue sounds exactly like @Kschep originally described. Except that because I had an automatic breaker, it would backfire (as the alternator lost power) and go black and quiet for 5-10 seconds as the breaker reset itself, and then I could pop the clutch and restart as soon as the lights came back on.
 

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