[Daves4wd]

Hey all my Sierra with 1.6 carb and 100amp alt keeps blowing the ignition fuse it ha a 20 amp and te auto elec said it would be fine but he's retard who dosent know his mouth from his ass has anyone had this problem? What size fuse should I run I'm currently stuck in the rain so I'm pretty much screwed thanks for the guys I can't search as i only have 10% battery left f**king iphOnes

[whincup]

if you have a multimeter start with checking all the wires. disconnect the wires at the coil, put the fuse in and turn the key to the on position, start with making sure the wires are getting the right voltage there. best place to start

some may disagree, but while fault finding like this, use a lower rated fuse. off memory (i replaced mine today so it should be correct) its a 15A fuse, use a 10A while doing this. it'll blow quicker therefore less risk of damaging wiring. i like to play it safe...

[stewy91]

Are you running a fuse from the alt to the battery

[jono165]

I have just mounted up a 110amp falcon alt in my sierra which I will wire up this week.

I will be doing the following.

want33s wrote:

My first one shit the reg and I found out they are 'self exciting' and will charge 15.5V max.

There are 3 steps to get the best out of these alts.
1 Fit alt (obviously )
2 Upgrade power cable between alt and battery. (130+Amp cable)
3 Fit a relay triggered by ignition and supply battery voltage to sense terminal on alt to avoid voltage drop in crappy Suzuki wiring loom.

[Daves4wd]

Ahh ok then we'll the auto elec said to run a 15 amp fuse it blew later on that night so put a 20 and it lasted till last night so I'll try figure it out wiring isnt my strongest point lol but I should hopefully work it out thanks for that guys

[whincup]

Daves4wd wrote:

Ahh ok then we'll the auto elec said to run a 15 amp fuse it blew later on that night so put a 20 and it lasted till last night so I'll try figure it out wiring isnt my strongest point lol but I should hopefully work it out thanks for that guys

REMOVE THE 20 STRAIGHT AWAY. if something is blowing the fuse, it means theres a problem. if you put a bigger fuse in all that will achieve is the wiring melting before the fuse does.

[Daves4wd]

Oh that's not good hopefully I can figure out what the problem is what power will run through the ignition wire??

[buzbox]

I had a similar issue with my vit when I was replacing the alternator, In my case the fuse would pop as soon as I go to turn it over. Check that the power lead going to the alternator ISN'T touching the body of the alternator.

It had me stumped for a few hours, I'm lucky my auto elecy is a cluey bastard, he also gave me a little ceramic spacer type thing to use. I felt like a dumbass after he told me though.

[Daves4wd]

It's all covered and nothing is touching I might get a multi meter tonight and see what it says Thanks for that clue

[Teracis]

Hah I've just returned from a week away and the mrs tells me my rig won't start, nothing turns on e.t.c.

There's a 20A fuse about 200mm from the battery which powers the whole truck, bar the starter itself, and of course this was blown. So this afternoon I take a look and try to find the problem, everything seems fine, all good, tested all the wires with a meter e.t.c. new fuse in, all good, start truck, all good, (used 15A as that was all I had for a replacement) about 30 seconds and pop goes the fuse, truck continues to run because alternator is now powering the whole thing.

So we let it run for a while, checking voltages e.t.c. with the fuse blown the battery is isolated from the rest of the truck and is only at about 10V (it still started the engine though) whereas the alternator is pushing nearly 15V.
Maybe this is the problem we decide and get the clamp meter out, find a 20A fuse to put in and while anto86 holds the meters, I put the fuse in (not long enough to blow, just long enough to see whats going on) and sure enough the alt is pushing something like 30A back into the battery, we do this a couple of times for a few seconds and it reads lower and lower until it's back under 20A and I just leave the fuse in and it holds.

All I can think is that either the battery is cactus and that's causing the alt to push too much current through it, something is shorting (why did it clear itself with no trace while we were measuring it) or maybe just maybe the regulator in the alt is rooted and pushing out too much voltage causing one or both of the above.
If any of you have any other ideas let me know, as a sparky I know there's always a reason, I just have to find and confirm it, I just thought I'd post this as it may help the OP.

[Daves4wd]

Ahh ok the. This helps me a fair whack the battery is a couple months old and the alt I have no idea got it second hand it's started when a screw driver fell and hit the alt earthing the inside to the outter I might see If I can get a resistor for it to keep it at 15amp?? Possible I've got no idea I might save up and by a new alt or get a reg and learn how to fit it got to learn somehow hahaha

[Teracis]

Daves4wd wrote:

Ahh ok the. This helps me a fair whack the battery is a couple months old and the alt I have no idea got it second hand it's started when a screw driver fell and hit the alt earthing the inside to the outter I might see If I can get a resistor for it to keep it at 15amp?? Possible I've got no idea I might save up and by a new alt or get a reg and learn how to fit it got to learn somehow hahaha

Ok that doesn't sound great, have you measured the output voltage at the alt? Have you checked the alt for physical damage? Does the fuse blow as soon as you put it in, or once you start the vehicle?

Lots of little things like that will help determine/exclude a huge amount of faults. I.E. I know there's something funky going on because mine doesn't blow until the engine is running and the alt is pushing current back into the battery.
If for example yours blew as soon as you put the fuse in with the ignition off, you'd be fairly safe to assume you had a short circuit maybe due to a wire rubbed through or similar.

Keep us posted either way.

[Daves4wd]

It's only blown the fuses at night for some resin the alt body is in good nick been buried in muddy water a couple of times hahah I know that's not a good idea I've stopped that now it blew when I started it with 15amp but with the 20 it's fine could it be when the battery gets drained to far with everything going ie lights heater wipers radio and the alt over charges the battery causing the fuse to blow?? I hate electricity me and it don't mix well at all except wirin a head deck and amp that's all I can do hahhaha suppose it's a start

[whincup]

so its blowing a fuse for the wire that runs from the battery to the alternator? the alt puts out up to 45 amps IIRC...

[Teracis]

whincup wrote:

so its blowing a fuse for the wire that runs from the battery to the alternator? the alt puts out up to 45 amps IIRC...

It sounds like he's having a similar problem to mine, the fuse I have has been put there by whoever owned it before me, there's no way it's factory, I'm yet to check my mr's brother's zook which I know was stock when he got it to confirm my theory.

[Daves4wd]

From standard it's should run a "fuse wire" not a actual fuse or it should have no fuse of any sort as the age of the car Apprently that's what I've have been told from my pathetic auto elec

Whincup it blows the white and green wire I think it is not the charge wire if it burnt out my charge wire then I'd be worried its 4 gauge power lead that I had since Ive had since my second amp witch was for a compositor witch turns a small charge into a larger charge

[Shansh]

mine does the same thing after a rebuild, blowing ignition fuses after running for about 1-2mins, it never did it before. I fiddled around a bit, decided to try removing the resistor between the coil & earth. It ran without blowing a fuse for maybe 20mins then the fuse went again.............will try the alternator/battery situation. I am pretty sure my battery is cactus & I am going to put a 110A alt in it.

[whincup]

Daves4wd wrote:

From standard it's should run a "fuse wire" not a actual fuse or it should have no fuse of any sort as the age of the car Apprently that's what I've have been told from my pathetic auto elec

yeah thats correct. some people add fuses in there though...

Daves4wd wrote:

Whincup it blows the white and green wire I think it is not the charge wire if it burnt out my charge wire then I'd be worried its 4 gauge power lead that I had since Ive had since my second amp witch was for a compositor witch turns a small charge into a larger charge

green and white wire? my wiring diagram says green with white trace is brake pedal switch to reverse lights, white with green trace is something to do with indicators/hazards (they could be the other way around)... thats an SJ413 manual...

[Daves4wd]

Well I just got a multimeter Los later in I be checking the car for what charge it's giving and what not never used one any tricks to using one or just go for gold???

[Teracis]

Daves4wd wrote:

Well I just got a multimeter Los later in I be checking the car for what charge it's giving and what not never used one any tricks to using one or just go for gold???

Check what range you're in, don't set it up to measure resistance or amps and then go to measure voltage, you will pop a fuse :p

Other than check what settings you're about to use before you stick the probes on, go for gold.

Ideally you will be checking your battery while engine is off, then while its on, correct my if I'm wrong but it should be in the vicinity of 12v while off and with the engine on and the alternator charging it should be something like 13.4v or 14v

If you think you have a wire rubbed through. Leave the car off (not started). Set your meter to resistance, put the probe in to the fuse holder where it's blowing (not the battery side of the fuse the other one, to confirm which side set meter to volts and check to ground (body or negative of battery) to find out, one will have voltage, go back to resistance and check from the other one to the body, with and without the ignition on but the car not started.

If you get a circuit from the body side of the fuse with the car off you might have a wire rubbed through, you should be able to tell by the readings, if say it's 30 ohms then it's probably running through something (good) if it's say 0.5 ohms, you may have a wire rubbed through directly onto the body.


This all depends on whether you have got it to stop blowing fuses yet, if it only does it when the car is running but not when the engine is off but everything is turned on then it's something else :p

That should get you started.

[Daves4wd]

Ok I'll check it out tomorrow after work I've just got no idea on how to use the thin so many settings and I get confussed real easy with wiring but I'll read the booklet I got and do them checks you said to do and I'll let you know hopefully I can work it Thanks for the help buddy

[Teracis]

Daves4wd wrote:

Ok I'll check it out tomorrow after work I've just got no idea on how to use the thin so many settings and I get confussed real easy with wiring but I'll read the booklet I got and do them checks you said to do and I'll let you know hopefully I can work it Thanks for the help buddy

No problem, my advice comes with no warranty though :p Like I said just make sure you check which setting it's on before you go to measure.

A lot of people forget that while it's on amps it has the properties of a plain old piece of wire, if you have a good one, a piece of wire with a fuse :p

[Daves4wd]

Do I measure it in dc voltage?? These things confuse the hell out of me I've got a sca ut39a multi meter

[Daves4wd]

I mesured it and the battery is holding 12.4 volt and charge is 14.4 and 14.8 with lights on dos that make sence??

[whincup]

its 14.4 while charging, then 14.8 while the lights are on?? then definitely alternator regulator, whatever its called

[Daves4wd]

So I need a new regulator for the alternator is that easy to do?? If so I might get one off egay and fit it myself need to learn somehow hahaha

[Teracis]

Daves4wd wrote:

So I need a new regulator for the alternator is that easy to do?? If so I might get one off egay and fit it myself need to learn somehow hahaha

See if you can borrow one or test someone elses first, if it's not still blowing fuses just keep one handy for if it happens again so you can get home, that's all I'm doing. If it blows while running, it will be all good to throw a fuse in, start it, keep it running to drive home and then deal with it again then while the problem is still there.

That said I also have a fire extinguisher on board.

[Daves4wd]

Oh that's comforting a fire extinguisher hahah seems to happen and night when things are on for a while see what happens but it'll work out I'll save for a new alt and keep this one as a spare thanks for te help this thread might alot of people now

[Teracis]

Daves4wd wrote:

Oh that's comforting a fire extinguisher hahah seems to happen and night when things are on for a while see what happens but it'll work out I'll save for a new alt and keep this one as a spare thanks for te help this thread might alot of people now

Surely there's someone in melbourne who would swap with you for a few days to confirm it's your alt? Buying a new one for a test seems a bit expensive, what about a cheapie from a wrecker?

[Daves4wd]

That's what I'm running at the moment I'll stop past my mechince after work and see what he says or see if he knows a reliable auto elec in melb to many people down here just want to make money and do nothing for it hahahah a new alt off eBay is $150 ish and $85 from Wreaker if they have one and $400 from a auto elec