Coolant light Gremlin - Still on & off

So my coolant light continues to go on/off. Replaced radiator overflow tank sensor; cleaned washer fluid tank sensor, 50 Amp fuse fine. Now thinking FCM or ECM or handshake. There is a pattern: light comes on if temp gauge goes slightly above mid line; off when it drops when gauge falls to slightly below. Seems electrical & sensor-based. Fan & AC working fine. I think I may just live with it until something more definitive arises...