Low coolant level light has been coming on now intermittently for a few weeks even though fluid level is good. Interestingly, the coolant level switch is normally closed (with reservoir full) and routes through the BCM to the dash indicator. Pulled off the connector under the coolant reservoir and put a jumper across the terminals. If the light is on, it won't go off immediately. I shut off the engine, re-started and the light stayed off.
Wound up removing the reservoir and flushing out with a hose. Some debris had blocked the float from sliding up and down. Seems to be working properly now. Probably a good time to also flush the cooling system anyway. For that matter, at 160K miles, should think about replacing the timing belt again and the water pump while in there.
Oppie