Question: My alternator warning light is on. Can I
keep driving anyway?
Answer: Yes, but probably not for very long. If the
alternator warning light is on, it means your charging system
is not producing enough current to meet the electrical needs of
your vehicle and to keep the battery charged. That, in turn,
means your vehicle is running on borrowed time off the battery
alone. You can keep on driving as long as the battery has enough
juice left in it to keep the ignition system, fuel injectors,
fuel pump and other electrical accessories working. But sooner
or later, the battery will run down and your engine will die.
How long this might take is anyone's guess. If you're driving
during the daytime and aren't listening to the radio or running
the air conditioner, the battery along might keep you going for
four, five, six or more hours. On the other hand, if its nighttime
and you have the lights on, the heater or air conditioner and
radio, you might run the battery dead in an hour or two.
A warning light should not be ignored. It usually means something
has failed and needs to be fixed -- the sooner the better in this
case.
Sometimes the alternator warning light will come on, (or the
amp or voltage gauge will show discharge) when nothing is really
wrong with the charging system. It's a gauge or light problem.
One way to tell is to turn on the headlights. If the headlights
shine with normal intensity and do not change as you rev the
engine, all's well with the charging system and the problem is
in the warning light or gauge circuit. But if the lights are
dim or get brighter as you rev the engine, you have a charging
system problem that requires further diagnosis.
Any of a number of problems can cause the alternator warning
lamp to come on. If the alternator drive belt is slipping, has
broken or flipped itself off the pulley, the alternator will cease
to produce current and the warning light will come on. If the
regulator that controls the alternator's output has failed, the
warning light will come on. And if there's a wiring problem in
the charging circuit, the light will come on.
