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Discussion Starter #1
Hi, Got a 1.8 turbo, last week the fuse box atop the battery melted,(like 100+others Ive heard about) wife had it replaced out on the road $300.00
Yesterday the Alt fuse in that box blew , the alternator harness looked bad so I replaced it.
The teminal where the alt bolts down gets REAL hot when the fan comes on, cable seems alright.
Could this be a fan going bad because of high resistance?
BTW this should be a recall, fire or explosion waiting to happen with a burning box above a charging battery, can anyone say hydrogen bomb!
any input apreciated
Mark
 

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Chances are the the main charging cable was the only bad part. You needed not buy a whole new harness. The charging cable in the new harnness is in my and a few others opinion with this problem , too small. So yes, it will get hot. Make a new cable using at least 4 ga. stranded wire. Parts are about 20 bucks . Disconnect the cable at the altinator and link fuse box and tape off. Route the new cable keeping away from the hot parts of the engine and reconnect the altinator and fuse box. This should prevent any more fuse box meltings at the altenator connction. There are 3 green blade fuses on the battery fuse block nexted to the link fuses. If your cooling fans are drawing too much one or two of them should blow before any real problems happen. They are the fuses for the fans.















































awg
 

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Discussion Starter #3
The first time the 3 30 amp green fuses melted the box, the alt cable end was also melted, this time just the fuse blew, now the cable is not getting hot, the terminal on the cable side is whats getting hot now.
Thanks
 

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This seems to be a common problem. I think it has to be a loose connection causing a resistive joint. There is a lot of current flowing through that cable - the junction with the fuse box will get real hot if that is not tightened down good.
The only other answer would be that VW underestimated the diameter of that cable to the alternator. I check mine occasionally and have never seen signs of overheating. And on a last note, look for a short (possible short in the fan). Disconnect the fan and run the car briefly. Notice any heating on connections.
 

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Hi Mark,

You can read a lot more about this situation and attempting to find the cause, the cable replacement as mentioned Stlbug, and more here -
http://newbeetle.org/forums/questions-issues-concerns-problems-new-beetle/52338-morav-needs-some-help-helping-someone-else-org-battery-fuse-box-issue.html

The correct diagnosis for the coolant fans can be found in a link in this post -
http://newbeetle.org/forums/2-0-liter-gas/52013-overheating-problem.html#post753256
and measuring the ampherage draw of the fans when running at the previously melted fuse location is a fairly simple thing to do. That wiring should have been badly damaged, and you make no mention of replacement.

Was there not any diagnosis done for the cause of the original meltdown?

To set your mind at ease the battery is sealed, not much chance for a related explosion, although a fire is a consideration.

MORAV
 

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Discussion Starter #6
Ah HA, morons put the fuses back in the wrong places or the new fuse box came with them in the wrong places! 40 amp is on the Alt circuit.
They told my wife it just happens to VW's no cause,thier diagnostic was box melted, replace it you know keep changing parts till you find the problem.
So I still need to find the cause of the original meltdown, the fan wiring looks ok and doesn't get hot, main thing this mystery is solved.
Thanks millions for the help and wiring diagram MORAV
 

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I never even considered asking if the fuse amperages were right. And on that note, you probably have the larger alternator so while the fuse boxes are the same, the fuse is a larger size. Wanted to catch you while you were on here. It is shown on the fuse panel diagram but could easily be missed.

Alternator size - Fuse amperage
90A - 110A
120A - 150A

Oddly, I have not found where the larger alternator uses a larger gauge wire, never even considered this could be a problem, but since the 90A alternator design probably preceedede the 120A alternator, the wiring too was probably engineered for the 90A. The alternator on my '02 is badged with the 120A in view. Not so on my '05. Other than by VIN run at the dealer I can't tell you for sure how to tell, but I'm guessing the T with sunroof, etc, and my Vert with power top and Monsoon radio are examples of models that would use the larger alternator.

M.
 

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Discussion Starter #8
Yea 120 Amp alt ,covertable GLX with all the xtras,so HO alt, Yea the alt 150A fuse is on S164, and the 40A fan fuse on S177.
I'm going to double check all. hard to see the markings. dealer run VIN for the alt wire, there are different ones, dont't know if its a larger wire or different other wires in the harness
I'm not very impressed with VW.
Thanks alot for the help MORAV
 

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If you'd complete your vehicle information, e.g. year, model, engine (although I know it's a 1.8T and I now no it's a Vert, still need the year), I can pull up the wiring diagram. As metric gauge wire seems to always be closest to an odd number AWG, I would go to the next larger even AWG, have a single cable made up (with the right terminals professionally crimped and/or soldered onto the cable) to run from the alt to the fuse box and just not connect that wire in the harness. NOT running that heat through the harness isn't a bad idea anyway.
 

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Discussion Starter #10
I found the correct wiring, installed all the fuses and wires in the right place and everything is working great! So far.
I think the original meltdown was from bad or corroded connectors on the 30A blade fuses, Gonna keep an eye on them, the problem I was having was the 40A fuse in a 150A circuit, high resistance bottleneck , why the terminal was getting hot and not the alt cable.
I would like to thank you again MORAV for all your help.
 

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Glad all is well and that I was able to contribute something. I have heard of more than one occasion where a poster found connections loose and/or corrosion on the terminals. I'm wondering what the cause. Wonder if it is the possible mixture of allows and/or through the repeated heat/cool cycles that is causing the nuts to become loose. Mine all look pristine, and I hate to mess with something that shows no sign of problem, but I'm considering die-elctric grease after a good cleaning, and either temporary loc-tite or nylon insert self locking nuts if I can find them in the proper material and thread size. Something is problematic to the "melt-downs", and seldom is any specific cause diagnosed, e.g. overloaded circuit, bad voltage regulator on the alternator, etc. Nor have I ever seen or read of any TSB from VW addressing the issue.

M.
 

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Discussion Starter #12
My bolt terminals were good I'm concerned about the 3 30A blade fuses where the first problem started, I think where it connects has issues so I too am going to look into a corrosion preventive cleaning checking program.
Now on to the top, rear window, transmission, 56000 miles its falling apart.
 

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Try This

For others checking this thread for melted fuse box! Save yourself alot of grief time and money! Don't change the alternator just yet...try this or have your mechanic do it.
After changing the alternator and having the car die again I realized it wasn't the alternator. After noticing MY fuse box was melted {apparently a common problem)and much research it came down to a bad crimp connector. I couldn't even touch it because of heat, as soon as I turned the engine on! So I cut the old one off pulled the wire alittle bit and replaced it with a $2 dollar lug from Lowes and wahlaa. cool as a cucumber, no heat what so ever. DONE!!! don't spend money on a new alternator or harness till you try this!!!!

 

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corrosion

Here we go again, why did vw put such important fuses and connections right next to the battery?? :confused: wrong place to put fuses. I think the connection compounded into a loose connection after it got hotter and hotter until the connector got loose from the crimp/wire which made things worst and it got hotter. Still a good find though :goodjob: To avoid future problems you might want to check the grounding cable under the battery tray which will also give you similar affects if the circuit looses it's chassis ground or too much corrosion.
 

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Help identifying connector!

I replaced the fuse box only to find that I am missing the connector for the S178, S179, S180 socket. I think that the p.o. removed the three wires and did ???

What is this part number and how do I order it. I can't find any info on the internet or here in the forums.

Thanks
 

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Your local VW dealer; can get you a new plug housing and/or replacement terminal ends, if they need replaced. Be sure; to have your VIN # on hand, as they will need it to look up your parts.

From a quick google search; this seems to be the it:

OE Fuse Box Connector Plug For VW Golf Jetta MK4 99-05 Bora Beetle AUDI A3 TT: about $17 from your local VW dealer:

VW part #: 1J0 937 773, I would confirm the part with your VIN #.

https://www.google.com/search?q=1J0+937+773&oq=1J0+937+773&aqs=chrome..69i57&sourceid=chrome&es_sm=91&ie=UTF-8
 

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Thanks

Thanks for the reply. I was really frustrated because the wires have been removed from the previous connector. Only one wire was left and I have no idea where the original red wires come from. I managed to locate a connector at the local vw junk yard, but they were already cut and separated from the car. I still have no idea where the wires come from and the beetle is just sitting in my driveway. I hate to pay for something that I know should be really easy to fix. I have looked at diagrams, but although I can do mechanics I am not great at reading diagrams.
 

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Here is a diagram; that shows the three wires, going into the plug but I do not know, if this is the same on your 1998 new beetle.

from left to right (standing in front of the car)

S180 coolant fan 30 AMP fuse,

S179 ABS 30 AMP fuse,

S178 ABS (hydraulic pump) 30 AMP fuse

http://ww2.justanswer.com/uploads/eurotec/2011-07-20_232626_87775448.gif

Tell us the color coding; of your wires and maybe someone with a 1998 New Beetle, can confirm the position of the wires for you.
 

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Yes, I had found this diagram, but my problem is that I don't know where I should connect the wires to. For example, I could buy the right gauge wire and then where does it connect to the abs? and is it the abs sensor or module or ? you see what I mean. I can't seem to locate instructions of where exactly each wire should go.
 
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