Battery is running dead while driving VW Jetta MK4 2.0L
Asked by Adam Jan 18, 2018 at 09:43 PM about the 2003 Volkswagen Jetta GLS 2.0 Wagon
Question type: Maintenance & Repair
Hi, i'm having an issue with my Jetta that is starting to do my head in.
The battery seems to be running its sell flat while driving the car. When the
battery is fully charged, I am able to drive the car for about 4-5 days within my
regular commute of 25-30 minutes each way. Eventually, the dashboard lights
start to come on and the car will come to a stop due to the powering failing
and it won't start again. Once the battery is fully charged, the car will start and
run as per normal for another 4-5 days. I've had the battery and Alternator
tested, and they are completely fine. I have no idea what is causing the battery
to die while the car is running. There seems to be some for of failure with the
charge coming from the alternator.
Any advice on what is going on here?
7 Answers
sound like a low battery voltage issue. if the battery is 4 years old or older it should be replaced. once the battery is replaced then you can PROPERLY test the charging system.
Thanks for the response... To answer your question, it has a brand new battery, and the alternator was also replaced before the test were done. Everything checked out fine. I’m curious to know if there is a fuse that runs between the alternator and the battery, or simply, could this be an issue with the cable/wires that return to battery from the alternator?
if you did not check fuses yes check those, other wise its off to finding a schematic and tracing down that circuit.
Thank you... any suggestions towards which fuse could be the problem?
should find one labeled charging or ignition but its always good to check them all. if you do not have a test light they are inexpensive and a great tool for testing fuses.
I would measure the battery voltage with eng running....Cheap or free DVM is all you need...and you should always read more than 12.5v....typically 13-14v...Then turn eng Off...put on headlights...read battery voltage ...Is it staying above 12v..? IF so,,then your battery and alternator are good...Lastly, lift one battery cable off battery when everything is off and not running...retouch it to battery post...you should only see a small spark...nothing very noticeable...if healthy spark,,then you have a unwanted drain 24/7...needing diagnostic..Also, be advised lifting the battery cable will most likely cause computer memory loss...
