low coolant warning 2001 jeep grand cherokee?

The low coolant light comes on often in my 2001 grand cherokee 4.0. The radiator is full, the recovery bottle is full. The temp is good. I pulled the connector from the float, jumped the wires in the connector, and removed the float manualy controling it. The warning is still on. Could this be a problem with the ECM? can it be reset? I prefer not to have to hit the reset button every few minutes as I drive.
Thanks Chuck