[net.auto.tech] generator light on

medhi@uwvax.UUCP (Deep {ankar} Medhi) (11/26/85)

 Nowadays when I drive and need to use defroster with
headlights on ( or wiper on ), my generator light shows up. My car starts
well and the battery is just more than a year old ( though once I left my 
headlight on for about an hour when my engine was not running).
Could it be a problem with my battery or is it the generator ?

 Thanks in advance.


 Deepankar Medhi

 medhi@rsch.wisc.edu

 ...!uwvax!medhi

richl@lumiere.UUCP (Rick Lindsley) (12/01/85)

It sounds like you are not getting enough juice out of your alternator, if
the battery is only as old as you say. Check the cheap alternatives first.

    * Check your alternator belt. If it is loose or frayed, then when
      you are running all those accessories you are using more juice than
      you are putting back. This is the most common problem. I had a
      belt once which was tight enough to keep things going normally, but
      with lights and blowers both on it gradually lost charge. When I
      stopped for lunch the starter wouldn't even turn over!

    * Check your battery. Even if it is only a year old, it may be having
      problems if you have drained it two or three times already (by leaving
      your lights on or something). This is something that many garages will
      do for you free, if you don't have the equipment to do it yourself, but
      beware of pressure from shady shops to replace the battery ("sorry, it
      looks shot") or the alternator itself ("gee, your brushes are worn").


If neither of these reveal anything (and keep in mind that a drained battery
that is only a year old is more likely a symptom of another problem rather
than a problem by itself) then take it into the garage and say exactly what
you said in your original query: "the generator light comes on when I run
both the lights and the defroster." Don't pre-diagnose by saying "something
is wrong with the battery", unless you are VERY sure that is indeed where the
problem lies -- let them find it out.

Good luck,
Rick Lindsley