If you have replaced both of these components and it still is a no go - just start looking for things like corroded wires or perhaps a blown fuse. Somthing to do with the alternator. For some reason the juce from the alternator is not getting back to the battery. If you stop at an auto parts store get a Haynes or Chilton manual (they have wiring diagrams in the back) just sit down in a quiet place and study the diagrams......Good Luck.........JeffAnswerMany autoparts will do electrical testing for either a minimal price or even free. That should take the guesswork out of the problem, and likely even save money: replacing perfectly good parts doesn't help (done that more times than I care to admit!)
Battery light usually means alternator not charging. Most common solutions would be be a bad alternator, bad connection, or loose alternator belt. If the battery and alt test ok than check the connections to the alternator and battery. You may also have a battery drain (something that is staying on and killing the battery)
I have a 2.0 1995 Mercury mystique the battery charge light was on no output on old alternator. Replaced alternator No output from new alternator "charge light out" (wiggle test wires& re-check wires) at alternator *still no output* is there a fuse that could be the problem or just another bad alternator... I would check the alternator plug before getting another alternator, it may be bad. And is a lot cheaper to replace.
The battery light isn't an indicator that the battery is always bad. What the light should really be is a picture of an alternator, but most people wouldn't recognize that. Have the alternator checked off the vehicle to make sure it is good, then have it checked on the vehicle, (many places like Auto Zone do this for free). If it's not charging on the vehicle, you could have an alternator fuse bad or your car might even have an inline fuse between the alternator and battery. Many Ford products have a large fusible link between the alternator and battery, and if it's bad, there is no power going to the battery from the alternator. Good Luck!!!!
I had this problem on a 1979 Mercury Grand Marquis- it turned out to be a short in the wire going from the alternator to the battery. It was intermittent, so it was very hard to run down. If the alternator checks good, the short/broken wire could easily be the culprit. Rocky_B - See my entry here for more things you might want to check: http://wiki.answers.com/Q/What_could_be_wrong_if_the_battery_light_stays_on_and_the_battery_still_runs_down_on_a_1996_windstar_after_installing_a_new_battery_and_alternator