Malfunction in the thermostat control system. The on-board computer reports problems with communication with the control unit, so a possible cause may be poor contact. The cooling system circuit is open, which may affect the operation of the power unit as a whole.this process determines the absence of a power source or ground, then perform a continuity test to check the integrity of the wiring, ignition switch, and other components. Continuity test must be performed with the power removed from the circuit while reading for wiring.