2002 Volkswagen Passat alternator?

RAYNEFOO93

MEMBER
2002 VOLKSWAGEN PASSAT
164,000 MILES

I was on my way to work and the battery light came on briefly, I was a little worried but figured because it went off I should be fine, I was almost to work when three more lights came on along with the battery light again, the lights were, ABS, the airbag light, and a triangle with a ! Sign in the middle with a arrow going in a circle around it, I was able to make it to the parking lot but not before accelerating became more difficult, I could not get my car past 45 mph, just put a brand new battery in so I don't see why it would be failing, I drive a 4D 2002 VW passat with a 4 cylinder 1.8l engine, I tried to have someone jump start it for me and it worked for about 5 seconds before stalling again, please help I have to get this car back n the road or I could lose my job, thank you.

2 Replies

CARADIODOC

MECHANIC
33,916 POSTS

The "battery" light has nothing to do with the condition of the battery. It means the generator is not recharging it as you drive. The resulting low system voltage will confuse the many computers on the car and make them do weird things or turn off. That's when those computers turn on their warning lights.

You will need to charge the battery at a slow rate for at least an hour, then it will give you from a half hour to an hour of driving time before it runs down again. That time will vary depending on how much you use the head lights, how often the radiator fan runs if you're in stop-and-go traffic, how fast you run the heater fan, etc.

When you try to get the engine started with jumper cables, if your battery is seriously run down, it will take from five to fifteen minutes before it STARTS to take a charge. That's why even if you get the engine started, it won't stay running. The battery is still dead and unable to power the electrical system.

It's the generator and charging system that needs to be tested. There's multiple ways the generator can fail. Not all failures turn on the "battery" light. When they don't turn it on, it means the generator is still producing a little current, but it's not enough to meet the demands of the entire electrical system under all conditions. Your mechanic will check the system for "full-load output", regulation voltage, and "ripple" voltage.