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vwnewton, VW Owner,ASE Master and L1 Advanced
Category: VW
Satisfied Customers: 307
Experience:  25 years of VW obsession turned into a job, last 15 years as a VW Tech.
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I am experiencing a charging system failure on my 2007

Customer Question

Hello,
I am experiencing a charging system failure on my 2007 Passat 2.0 FSI. The battery is not getting any charge from the alternator. The alternator has been swapped and does produce varying amounts of output as read from a volt meter to the bolt on the back but this voltage does not appear to make it to the fuse box. The cable from the Alternator to the fuse box is rather hard to trace as it goes below the block. Any suggestions on how to troubleshoot this further?
I would like to add that the car appears to be in some form of protection mode. The radio, AC, and power steering are all of with a battery indicator light that stays on.
Submitted: 5 months ago.
Category: VW
Expert:  Wolfgang replied 5 months ago.

Thanks for choosing Just Answer . I'm Wolfgang here to help!!

I am confident we can resolve your problem together. Please
understand that I don't know your skill level. In most cases when you have a problem
with the way the vehicle performs, specialized tooling is required to acquire computer
data/information or engine testing results. We didn’t build these complicated vehicles; we
just diagnose and fix them. Also understand that I can't see, smell, hear, or touch the
vehicle either, so it may take a few replies to get to satisfactory results. I am also going to
direct you with the fastest, easiest and most common things to check first. Please be
patient and permit me to do what I do best.
I also try to give all of the information you may need, expecting a “positive rating” in
return. I will also continue assisting you after you have rated me, if necessary. If there
is any reason I cannot get a positive rating, please let me know why “in advance”, so I
can go another direction for you. I am sorry you’re having this problem; I’ll help you
through it.
Below is my first answer or request for more information. If you do not understand it, or you need more information from me, or need me to go in more detail.

ok did you check the high amp fuse on the fuse box .

please let me know!!

Customer: replied 5 months ago.
all fuses have been checked. The suspected cable leading from the Alternator to the fuse box does not have any voltage at the fuse box when the car is running.
Expert:  Wolfgang replied 5 months ago.

what is the voltage from back of the alternator to the battery negative cable?

Customer: replied 5 months ago.
I get about 14.4 and more if I rev to higher RPM's I did notice that this voltage is not always there right away. I have to test a little more but it appeared to kick up after bringing the RPM's up a bit and then it would stay constant near 14.4. Unsure if this is as expected.
Expert:  Wolfgang replied 5 months ago.

ok i need you to measure the back of the alternator to the cable connection at the fuse box . i want to measure the voltage drop of the cable itself!!

Customer: replied 5 months ago.
OK, just completed. There are some conflicting wiring diagrams out there but I believe it to be the cable farthest left and on the lower bank. I had initially suspected it to be second from the left with the black bolt head. In any case, the one farthest left is a flat zero with positive at the back of the alt and negative at this terminal. The one second to the left reads 13.6 with the same test.
Customer: replied 5 months ago.
Taking the car to the shop in the AM as I have exhausted the time I had to try and deal with it. Thank you for your brief assistance but I did not receive any real advice in this instance.

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