Why's my fuse box melting???

[1.8TTURBO]

Hey guys, my fuse box all of a sudden decided to melt by itself ...

no kidding the first fuse from left to right melted and the fusebox aswell melted,

i've heard many things of what may cause it, but need to know since i bought a new one

and don't want to f*ck it again...

So I notice my engine (oil temp) where rising, reason: radiator fans where shut... they goes on

ONLY when I turn on the a/c .

So I've heard about changing the two fans, replacing just the big one,...

replacing the fan control module, the a/c relay, just replacing the box...

I need reasonable thinking, what should I do, check and how to check them, before i start

buying and spending money i don't need to spend...

Modified by 1.8TTURBO at 9:03 AM 12-11-2009

[naconi]

If you are talking about the one on top of the battery, I had the same thing happen to a 98 beetle. It is the fuse for the fan, mine didn't melt too bad so I didn't buy a new fuse box. I just replaced the fuse and I haven't had a problem for about 1 year.

[1.8TTURBO]

bump

[burble X2]

i have a newer mint condition fuse box with all new fuses in it, along with the alternator wire which you will probably need to replace too available. same thing happened to me a while back, i replaced the box and the alternator wire, and it hasn't given me any trouble since then. i bought this box+wire as an extra, and i'm not going to need it. PM me if you're interested.

[Gott2Jett]

pm sent

[x00001633]

read my posting
http://forums.vwvortex.com/zer...81857
i am having similar issues with mine.
i just installed a new fuse box today and is heating up again.
the problem may be your alternator harness thats what i intend to replace next.

[x00001633]

also if it is the first wire from the left, if you are looking at the engine bay fuse box from the front,
then this wire is the +ve of your alternator

[x00001633]

here is a picture of my melted fuse box before ui replaced it
http://img340.imageshack.us/gal.php?g=1004850.jpg

[1.8TTURBO]

I replaced the fuse box with a new one, and the same fuse is melting again is the first one from left to right... any advice, suggestions , ...??? tia!

[x00001633]

I am having the exact same issue as you are right now
I have the 2.0 GLS engine but the alternator, fuse box and alternator harness are the same in both.

I replaced my fuse box this morning. I filed the carbon from the contacts put on an electrical contact grease to make sure the contacts were really good and clean and it is starting to heat up again, i could smell the plastic and see smoke starting to come from the black wire.

I killed the engine right away before it got a chance to melt it again. VW dealer charged me $150 for that fuse box and i definitely don't want to be swapping that out every time.

For some reason, too much current is being drawn down that cable causing the black alternator cable to heat up and melt the fuse box.
There is a 110A fuse there that should pop to prevent a fire but it does not.

My alternator is <2 months old, my fuse box is brand new.
the only part left for me to replace is the alternator wire harness so i will be doing that on Tuesday most likely when i can get the part.
I am waiting to confirm the part number for the harness. Ill let you know if it fixes the problem for me.

[mcTT]

Maybe the oem alternator wire is too small?

I put an additional inline fuse and new wire. Haven't driven it much since so no word on effectiveness.

[mohadib]

ahh, im having this problem too. My customers cars would just die, sometimes the dash board warning lights would go nuts too. SO im hoping its due to a bad wire to the alt. Anyone else with this problem have luck by replacing the alt? Could a dead battery cause the alt to send too much amps for that wire?

On the car in question I measured the output of the alt with the car running. Was only 14v. Could the alt going bad slightly cause a drop it charging volts, thus causing more amps to be pulled though the wire and resulting in the melting at the fuse block? Im grasping for anything here

Heres what mine looked like:

[hollywoodman]

this is a normal problem. you guys have a bad connection somehwherer............. ie battery clamps..............back of the alternotr.............. cable fromt he altnerotr to battery.............. also replace the alternator cable and fuse box as one.....

[1.8TTURBO]

well my alternator cable seems fine, in fact, my problem is in the first fuse from left to right, the green ones from the pic above

[1.8TTURBO]

i just took out the a/c control module and seemss fine. what else can i check???

[groggory]

When you say 'seems fine'...are you checking with an ohm meter? Or just visually?

You need to check from a nice chassis ground (eg engine block) to each other ground point.

Also check from the top of your battery terminal to each hot point in that alternator circuit for voltage.

You need to check electrically not visually in this circumstance.

[1.8TTURBO]

ok thanks, but i've heard that the fuse my car is melting does it b/c of a/c problems it's a fan problem but could be the relay, the module or the fan itself... i'm gonna check electrically now, lyk

[groggory]

If you have one, use a clamp style amp meter.

Basically you just put the loop around the cable and it'll tell you how much current is flowing. Turn various things on and log how much current flows when the different things are on. Then you can find the current pig that is melting your box.

[x00001633]

so
Have ordered the alternator wiring harness, ill be picking it up today on the way home from work and hopefully installing tonight or tomorrow. I really hope this fixes the problem.

Also, a mechanic suggested i test the battery as there may be a possible shorted cell making the alternator work like a dog and draw high current.
I did have the battery professionally tested and it is fine. but maybe you should test yours too.

Will update when I have installed and let you know if it worked.
Wish me luck!

[1.8TTURBO]

thanks buddy, wish you best of luck!!!!
I'll be checking my battery too... i also suggest to check the ground cable from the alternator, it goes to the block.

[groggory]

Quote, originally posted by 1.8TTURBO »

thanks buddy, wish you best of luck!!!! I'll be checking my battery too... i also suggest to check the ground cable from the alternator, it goes to the block.

So did you check all of your connections with the ohm meter? Do you have any measurements that back up you replacing your stuff? Or are you just throwing parts at it?

[x00001633]

Didn't check resistance w/ ohm meter. just tested connectivity,
But, I had to replace those parts. Did you see my pictures. those parts have to be replaced regardless of what an ohm meter showed. Especially my use box which had melted.

but, tonight I plan to
- replace alternator harness
- Test battery voltage cold and with engine running
- Test alternator voltage w/ engine running.
- Check Resistance w/ ohm meter.

Would you happen to know what the ideal readings should be?

Thanks

[groggory]

Battery should be ~12V
Alternator should be ~14V

Cables should show a reading of <.5 ohms

Test cables, then across connections, and just all that jazz. You're looking for a bad crimp, a bad connection, a bad cable, a bad fuse, some corrosion, whatever

Where you put the leads when you test resistance makes all the difference as to figuring out the problem.

Test all that stuff with the battery disconnected to make it easier on you.

Take a piece of paper and write down where you put the black probe and where you put the red probe and what the resistance was. Then post all that back for us. That way we can tell you if you forgot to measure something or if you measured from the right points. I know it's a pain, but being that this is a forum and we're not there to see that is how we can best help.

[x00001633]

sure will
thanks for this good info ill update hopefully later this evening (weather permitting) or tomorrow evening at the latest

Thanks again

[x00001633]

Hi Guys,
replaced the alternator harness tonight
Ok, its looking like good news. had the engine running for over 10 minutes with all accessories going, lights, heated seats wipers etc and the cable barely warms up.
last time i did that with the older alternator harness i would have had to shut the engine off long before that.

I did some measurements, here they are

(measurements with engine OFF)
New alternator harness resistance: 0.2 Ohm
Batt Voltage Cold: 13.1V
Resistance across 110A fuse in engine bay fuse box: 0.2 Ohm
Alternator Voltage (Cold): 12.7

(measurements with engine ON: No accessories)
Batt Voltage: 14.67V
Alternator Voltage:14.5

(measurements with engine ON: ALL accessories ON at once)
Batt voltage:12.75
Alternator: 12.6

Hopefully I am not jumping the gun but seems like we are in good shape now. i need to put everything back together and tie up the cables. I think then i will take it for a drive for 30 mins or so and make sure all is good.

Want to thank you all for your help and hope nobody else or myself doesn't get this problem again

[x00001633]

So drove the car last night for about 40 minutes,
Was -8 last night so had the heated seats cranked up and heater going on full.No problems.

Drove into work today too and everything looks good.

[x00001633]

all in all it cost me ( Canadian Dollars)

$28.00 one day rental car
$160 tax for engine bay fuse box
$3 for 110 Amp fuse strip
$120 for alt harness

So not too bad i guess could definitely be a lot worse.

[transient_analysis]

I actually had the plastic around the green fuses burn up.. on the side opposite the battery.

All the other nutslooked a little 'worn' so I took out all the fuses and cleaned both the fuses, and all the bolt/nuts before reassembling the entire thing.

Sounds like the battery fuse box needs to be added to the 100k checkup.

[x00001633]

I wish VW would do the due diligence and re-call the crap. seems this problem is a little too common across VW and AUDI.

[groggory]

Maybe someone should make a nice aftermarket unit that fits in the stock spot.

[x00001633]

did you fix it yet?
Whats the status on your car right now?

[BassNotes]

The bad connection is right where it's heating up--on the end of the alternator wire. The ring terminal on the end is prone to getting corrosion and other muck between itself and the copper strands.

It's so common on VWs and such a potential for fire or other damage that I'm surprised that to my knowlwedge there's been no recall or campaign.

Get a suitable ring terminal. I don't remember the exact size, I think the wire is the equivalent of 4 AWG and the ring opening is about 5/16". You can get them at auto parts stores, hardware stores, etc., maybe about a buck each or so. You'll also need a large crimper or crimping pliers.

Cut off the old terminal. Cut off the end of the wire to where the strands are in good shape. Strip the insulation back enough for the new terminal. Crimp the new terminal tightly onto the wire. Install it onto the screw post on the fuse panel.

If the fuse panel is in bad shape, you'll need to replace that too.

[1.8TTURBO]

my alternator cable is good, so is the alternator and battery.
checked the a/c control module good
checked all connections and are also good..
a friend checked it with a voltmeter and says everything was normal
all my fuses are new

same problem:

fan fuse melting

now the problem is:

the turbo s use a diff. fan (the big one) it has 3 speed and a 4-pin harness
cant find it locally, the price on the dealer is $380
anyone knows a replacement that will fit???

[x00001633]

You say your cable is good?
that cable (if it is still the one in the picture, does not look good) you can see corrosion on the copper and there is too much copper exposed.
you really need to change that your can can go on fire. the fuse does not stop the current it keeps burning. when it happened to me was -10 outside but on a hot summers day who knows what could have happened.
what was the resistance on the cable?,
measure the resistance between different points of the corroded contact and the other end.
should be 0.2 ohms no matter what.
the part number for the alternator harness is 1J0 971 349 HG (with A/C)
1J0 971 349 HF w/o A/C
and it is good for MKIV jetta's 01-05

cost me $120CAD from VW dealer in georgetown ,Ontario. car has been solid since no electrical problems to report

[BassNotes]

Is it the first fuse on the left that's melting?

If so, then your alternator cable might not be good, at least on the end.