2001 Sonata Warning Lights

Without any apparent mechanical changes, after a warmup period of maybe
five minutes,the battery and brake warning lights come on and usually stay
on. Also at times, the speedometer and tachometer needles drop to Zero
while the car is still operating normally, then the speedometer needle
starts working again, alone, while the Tach is still at Zero. At times,
the 'air-bag' warning light also comes on and stays on. A/C still pumps out
cool air, but not at full volume for any selected speed. I suspect a loose
connection, but would like to know where to start looking. Any help is
appreciated.

 

Start looking at the alternator. Low voltage can cause any number of odd
occurrences.

 

I had an Excel with and instrument panel that did very strange things.
The turn signals would cause the tachometer to go up and down
and stuff like that. I was all because of a broken ground connection.

- Mooron