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?
2002 Volkswagen passat 2.8
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, but the alternator replacement seemed to not fix the issue. What could it be?
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
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?
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
12 years VW Dealership Forman/Technician ; VW Factory Trained ; 25 Years ASE Master Technician