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Discussion Starter · #1 ·
Hello,

I recently changed out the alternator on a 2007 2.5 Beetle. Alternator spins but won't charge the battery, I out a voltmeter on the battery and watch the battery slowly die. Anyone have any ideas as to what the issue might be? It looks like everything is plugged in from what I can tell.
 

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The large wire that is connected to the bolt and goes to the battery looks like it's connected correctly, BUT what is that slice in the insulation? Does that sever the wire? Is the wire in that hole blueish? If you put the red lead from a multimeter on that bolt that the battery wire is connected to with the car running what is the reading? Now move the red lead to the positive battery post, what is the reading? I would guess your big wire is kaput.
 

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Discussion Starter · #5 ·
I believe you are correct. I have no continuity between the connection at the alternator and the far left post on top of the battery. Guess I need to get a new cable.
 

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Discussion Starter · #8 ·
That would be your problem. Good job tracking it down.
I spoke too soon. I've been working on 2 cars the past couple of days and my mind has been jumbled. I did a volt check not a continuity check. I just walked over to the car and did a continuity check from the alternator to the cable that connects to the distribution block on top of the battery and the battery itself and I had .6 Ohms.
 

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Yes, if the alternator is putting out around 14v like it should be at that bolt where the sliced cable hooks up and then testing the battery terminal the reading should be exactly the same. If its not something in the path between the alternator and the battery is bad, either the cable or the fuse block. Those fuse blocks on top of the battery are known to melt and cause problems also. Doing it this way avoids tossing parts at a problem till you finally get it right.
 

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Discussion Starter · #12 ·
I'm slowly working my way through this, threw out my back so I haven't been able to do much. Before putting everything back together I noticed a burn mark on the plastic that connects to the alternator. Any thoughts as to why that might be?
 

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How long have you had the new alternator in there, and exactly how many volts is it putting out when the car is running? Measure with your multimeter at that bolt. Have you checked the fuse block on top of the battery for melted connections?

Where did you get the alternator, parts store alternators are often remanufactured junk with a “lifetime” warranty, sometimes you replace them multiple times to get a good one.
 

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Discussion Starter · #17 ·
Car is fixed! The plastic that surrounds the back of the alternator was raised higher than the back of the alternator bolt so it wouldn't allow me to push the cable all the way down. I put 2 washers on the bottom of the alternator bolt to clear the plastic and voila! I believe the issue for the melting plastic was the cable bouncing around creating a high resistance to the cable causing it to hear up. Thank you to everyone that helped offer advice!
 

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Hmmm, sometimes, rebuilds are fitted with new parts like the plastic back cover or are sometimes totally different shape, just don't fit that same, as the original part. Glad you got it fixed and good work! :)
 
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