Does anyone know what this could be

You may have some grounding issues or some other electrical problem , look for any obvious wiring problems , check for good motor to chassis ground or corrosion at fire wall disconnects

Chrysler products are known to have computer problems with their charging systems so check the battery or alternator separately won’t find the problem. Your favorite shop should have the right equipment to test the entire system and find the problem. I have replace I don’t know how many Chrysler computers due to a internal failure in the computer.

A check gauges light just alerts you to check your other gauges. It's like a slap in the face to wake you up to the need to look. If this is accompanied by a dimming of lights, you might have a bad light sensor or other control. Or as it's nearly twenty years old, it might be an electrical ground problem, or maybe just loose battery cables.

Check the alternator belt too. It may be worn and slipping. If this only happens when you hit a puddle or in the rain, check underneath for a missing splash guard. Hope that helps! Jim