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.