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Will it "jump start"? If so, it's not the starter. If not, it could be starter, cable or other wiring problems. If it will start using a "jump start", you probably have either a loose or corroded battery connection or your battery isn't fully charged. If it's not fully charged it can be either a bad battery or the alternator. If you can't take it someplace to have the battery tested, try this simple alternator test: Jump-start the vehicle then remove the jumper cables. Borrow, rent or buy a volt meter and test the voltage at the battery. With the engine running at around 1000 to 1500 RPM, your meter should read about 13.5 Volts, +/- a half a volt. If it's close to that, have someone keep the engine running then turn on some of the accessories that draw the most current, such as the heater motor, headlights and rear window defroster. The voltage shouldn't drop with all of those accessories running. If the voltage drops below about 13 V under load, you probably have an alternator problem.

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βˆ™ 2006-04-05 14:30:17
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Q: How you diagnose difference between Alternator Starter or Battery going bad in a 1999 Volkswagon Passat?
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