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Twizzler
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Discussion Starter #1
What is the REAL reason the fuse block melts on top of the battery. I've read posts but they are always not positive as to the cause. Does anyone know a true and final fix for this situation I'm going to need a third fuse block for the top of my battery and alternator cable as this second set has melted and is causing intermittent power drops again.
 

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Too much constant current for the tiny fuse contact. It causes them to heat up and melt the plastic. I'd just bypass it with a better fuse holder.
 

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Twizzler
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447 Posts
Discussion Starter #3
Yes, its definantly too much current, mine melts right at the alternator cable contact to the fuse block. What were they thinking when making the contacts out of thin pieces of zinc coated alloy instead of thick copper. And of course the cable from the alternator is toast again as well causing power loss off and on.
 

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Twizzler
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447 Posts
Discussion Starter #5
I have read apost on another website answers.com or something like that where "professionals" answer your questions. A VW Technician (mechanic) said the reason the fuse block melts is that one of teh cooling fans has failed and that causes the alternator lead to heat up to the point of melting the fuse block housing by the alternator wire. Whatehr this is true or not I don't know. How could you test the fans? They apparently operate on two speed settings dependent upon the thermal switch detecting hot or too hot. The thermal switch itself sometimes gets replaced as it may be faulty and not putting the fan into the second speed. How could you test these components?
 

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Fan Failure

Hey there I'm a newbie to this wild world of car repair threads, and by no means a VW professional.

I happenned to find this thread whilst searching for fuse diagrams for my 98 New Beetle, as I recently over heated my car and realized my fan was not running.

I was about to bring in into my local general repair place but I thought I'd check the fuses before dropping it off.

Anyhow I found the Burnt up fuse that is mentioned in this and other threads here on this site.

I have yet to mess around with the temp switch to verify whether or not my fans will work without the AC on.

However I did turn my AC on to see the fans Spin, and I noticed that they were making a loud noise. I spoke to my father who uses to work his own cars mostly, and he suggested WD40 into the fan bearing, and to spin it by hand to see if there is any improvement.

Now that I sprayed so off brand WD40 into there the fans don't make the loud noise anymore.

I believe that if the fan is having problems spinning that this may be what is causing the extra current through the fuse.

When the professional said the fan was failing, it may be that it is just having problems with friction, from not being run for a long time.

I noticed my problem this Spring, and I use my AC as little as possible.

Instead of buying a $300+ fan I'm going to try to run my WD40'ed fan for a while, This is only my first failure so far.
 

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Twizzler
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447 Posts
Discussion Starter #7
I spun my fans by hand and they spin very freely, no friction. I haven't tried teh air conditioner check to spin them though. The VW tech did mention that just the a/c check isn't enough because it will only use one fan speed though.
 

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No NB Yellow Trifecta :(
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There is a test procedure for checking both fans; I'll have to look it up. When I had my first water pump failure on my '98 I tried everything else as I knew that WB/TB was expensive and at the time I had not taught myself how to do it, nor could I afford it.

Anyway from what I remember it goes somethign like this...

Disconnect the wiring harness from the control module (small rectangular box) located underneath on the drivers side, near the radiator drain spout. Use a jumper wire to connect some pins and I do not remember which pins to use; I do remember that if you do it wrong you can burn something out.

The result you want is, if the fan turns on, the fan is good.
 

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99 Beetle 2.0
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I have read apost on another website answers.com or something like that where "professionals" answer your questions. A VW Technician (mechanic) said the reason the fuse block melts is that one of teh cooling fans has failed and that causes the alternator lead to heat up to the point of melting the fuse block housing by the alternator wire. Whatehr this is true or not I don't know. How could you test the fans? They apparently operate on two speed settings dependent upon the thermal switch detecting hot or too hot. The thermal switch itself sometimes gets replaced as it may be faulty and not putting the fan into the second speed. How could you test these components?

I just had to test my fans. You need to junp the brown and either of the red wires to the battery to test them. I just had to hardwire my fans because the control modual is bad.
 

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Had the dealer replace the box and wire last month, cost me $500 and I had no fans so I could not drive to a local tuner.
So last week, when I finally drive it, if I turn the AC on.. all the check engine lights pop up, radio dies, and once I shut it down it's like the battery is dead. Let if rest for 30 minutes and it runs fine again, until I turn the AC back on.
I hate German car repair shops... :mad:
 

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285 Posts
Battery top fuse box burn...

I've heard some of the most ridiculous explanations as to why a fuse block would melt here in this thread.... Our cooling fans have nothing to do with keeping the fuse block, alternator leads or anything else electrical cool. The fuse block melts and burns because there is an unregulated amount of current coming from the alternator into that fuse block. Our alternators put out about 14 volts when working correctly. If the voltage regulator malfunctions that voltage can climb much higher and cause an over loaded circuit, etc. Normal voltage coming from the alternator should be about 13.5 volts. In our cars and most all others these days the alternator has a built in regulator that can be replaced. It is an all in one carbon brushes and regulator unit that lives inside the alternator... Start checking voltages with any multi-meter and you will be able to find where that voltage spike is coming from and fix it. Just because a garage says they work on German cars doesn't mean that they can fix them! Check your local VW dealers service department and see if they have any kind of recall concerning possible fires and melted fuse blocks that apparently have cursed our cars. This could be construed as a safety issue... Good Luck, JK
 

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member
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363 Posts
The fault simply lies with the fuse holder and the way they grip the fuse. At best, the design may on a test bench carry the rated fuse load and not overheat. However, in the New Beetle the fuse block sits directly above the battery and the battery vents corrosive fumes whilst being charged which then corrode the fuse holders increasing the resistance which in turn heats the connectors up. The hotter they get the greater the resistance.
Two possible solutions:
1...solder the fuses to the connectors.
2...cover the fuses and connectors in silicone grease to protect them from the corrosive battery fumes.
 

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I dont think you should do that

I spoke to my father who uses to work his own cars mostly, and he suggested WD40 into the fan bearing, and to spin it by hand to see if there is any improvement.

Now that I sprayed so off brand WD40 into there the fans don't make the loud noise anymore.

Instead of buying a $300+ fan I'm going to try to run my WD40'ed fan for a while, This is only my first failure so far.
IMHO I think it is a really bad idea to try to replace bearing grease with wd40. It is a solvent and will wash the grease away. SUre it may work for now. . .it will seize in a short period of time . . .again IMHO

bad hardware needs replacement.

The Lovely Laura's beetle died last night and I noticed the main wire from the battery to the fuse on top had looked fried. After looking, I do not note a way to get just the wire off . Came to look it up and saw this thread front and center.

Off to look for other threads but if anyone knows and can answer>> please do. From the topic I imagine all of you can tell me.
 

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Twizzler
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447 Posts
Discussion Starter #15
Just yesterday afternoon I replaced my totally crisped alternator wire harness to the fuse block and the fuse block itself with new ones, got them cheap off eBay.I also added thick copper strips to the fuse block contacts to increase the conductivity. When my block heated up it was VERY noticebly caused by the wafer thin contact strips that are made of some soft alloy that literally turns to ash eventually after repeated heating events; eventually breaking contact with the rest of the block and of course the heat begins to travel backwards up the alternator wire totally cooking it out. Mine was so bad if I bent it it would snap in half. Now that I have changed it all out all of my illumination is back to brand new and the car acts very responsive now. In all honesty I believe its the blocks contacts along with a bad voltage regulator on the alternator causing the meltdown. The block gets hot at different times not constant so that sounds like the voltage regulator putting out higher voltage than normal and at varying times, thats the same as the fuse block melting times. You may notice as well that the contact strips in the fuse block are stamped at differnt amp ratings from 100 on the alternator leads to 50 on other leads farther away yet the strips are all identical in thickness and composition? Thats odd. My alternator for my model year 2002 is rated at 120 amps? Thats higher than the fuseblock strip can handle according to the stamp max. amp rate.
 

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Returning senior member
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Vented batteries...

I have a sealed battery in my 99 1.8 and it always looks like new with absolutely no corrosion at all. I don't know why anyone would even buy a vented battery these days especially for our cars with the set-up they have. I've just come from my garage where I inspected my top of the battery fuse box and all looks to be in very good and clean condition. The metal strip fuses are specifically designed to melt and stop current from flowing if the amperage exceeds each fuses design limits. In order to protect the connected circuits it is a very bad idea to supplement any one of these strips for anything other than the designed gage strip. Extensive damage can be done to the wiring harness creating one of the biggest messes you will ever see. Be careful and good luck, JK
 

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Twizzler
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447 Posts
Discussion Starter #17
If those contact strips between the lead and the contact bar are supposed to be fuses they are very poor ones, they fail only after the fuse box has become garbage from overheating/over-amping and that takes up to a year in some instances. They will allow the alternator lead to fry and only then will they turn to ash, whats the point?
 

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Had the dealer replace the box and wire last month, cost me $500 and I had no fans so I could not drive to a local tuner.
So last week, when I finally drive it, if I turn the AC on.. all the check engine lights pop up, radio dies, and once I shut it down it's like the battery is dead. Let if rest for 30 minutes and it runs fine again, until I turn the AC back on.
I hate German car repair shops... :mad:
Quoting my own post :p
Anyway I charged the battery and had it checked today, my alternator is putting out 0 volts ??
Dealer sent me on my way with a dead alternator after raping me for $500 putting in the fuse box ?
 

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Twizzler
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447 Posts
Discussion Starter #19
I'm not surprised. The dealers around me know less about VW than someone who works privately on Vw's. I'm really happy with a local guy who charges ridiculously lower than the dealer and does the job right from the get go.
 

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Turbo Bug won't start now

I guess I'm kind of resurrecting this post, but the description fits. My daughter's Yellow Beetle wouldn't start yesterday after school. I went to pick her up, and just looked at the battery, to see that everything was connected. It was then I found that one of the fuses had "melted" in the fuse box that sits on the battery. I managed to pull the fuse out and replaced it with another 30amp fuse. It still won't start. However, I am able to push start her up and at least then we got to AutoZone. The tested the battery, and it still is just fine... but they aren't sure that the fuse block is my only problem here. They insist that something "must" have caused this. I'm not a mechanic and won't try to beat a man at his own game, but help me to be prepared when I take the car in to have it worked on. What questions do I need to be asking? What do I need to tell them to check and fix? I'm hearing discussion here saying that "spikes" from the alternator are causing the fuse block to overheat at the wires and fuses, causing the meltdown. Is this correct? Theoretically if I get the fuse block completely replaced the little yellow bug will be back on the road again?!?

Thanks for any advice you may have!

Regards,

cheer_dad
 
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