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.
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Start looking at the alternator. Low voltage can cause any number of odd occurrences.
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Klaus Macon wrote:

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
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