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jeffrey590, ASE Master Technician
Category: VW
Satisfied Customers: 2847
Experience:  12 years VW Dealership Forman/Technician ; VW Factory Trained ; 25 Years ASE Master Technician
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passat GLX: replaced the 02..short drive

Resolved Question:

I just replaced the alternator on my 02 passat GLX. I still only read 11.5v at the battery. The battery is new by the way.The car will not start after a short drive, and sometimes after sitting all night. I thought it was the charging system because of the 12v when running, but the alternator replacement seemed to not fix the issue. What could it be?
Submitted: 8 years ago.
Category: VW
Expert:  jeffrey590 replied 8 years ago.

There are a few things that can cause this...You need to check the battery cables for a good,clean connection and tightness...also you need to check the wiring at the alternator for good connection and also that the alternator ground is good...any of these will cause a low or no charge condition...also check for voltage drop in the battery cables ...Finally,test the alternator at the battery with the car running...should be 13.5-14.5 with engine running....if not the replacement alternator may be faulty or you may have a faulty connection or component in the circuit itself...It may also pay to check for a parasitic draw on the system if the battery goes dead overnight...your description sounds like you may have 2 seperate problems,so do each test one at a time until you locate the problem...jeffrey590
Customer: replied 8 years ago.
Thanks for the response. Assuming that the alternator is good the cables are properly connected and there is no drain, what components are inline that I can check or change to solve the issue?


Expert:  jeffrey590 replied 8 years ago.
There is a load reduction relay in the relay box that can give you a problem...I would also check that the body of the alternator has a good ground to the engine...This is fairly common on these cars...jeffrey590
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