Logic Circuit

Input signals from various sensors and switches are continuously monitored by the electronic control unit. With engine at operating temperature, a rapid temperature change is simulated by unplugging the coolant temperature sensor. The microprocessor in the control unit will compare this momentary temperature with the temperarture in its memory.

The control unit will recognize the abrupt temperature change as an open circuit, and is programmed to change the fixed operating mode. The control unit does not recognize gradual changes as malfunctions, and will continue to operate normally.