this is an indicator that there is a problem in the alternator,,,battery,,cables,,wires,,gr
ounds,,connections,,,or in some part of the charging circuit.
1. check battery first. 12 to 13.5 volts
2. check cables,,grounds,,wires and connectors. nothing loose and no corrosion,,heavy grease build up,,connections clean and tight,,corrosion can be removed with baking soda and a light application of water.
3. check alternator. most auto repair shops can test alternator while installed in vehicle. output voltage should be approx. 12 volts engine off,,,,14 volts engine on.
get this fixed before you get stranded on the side of the road.