MCU Inputs

Oxygen Sensor
The oxygen sensor provides a variable voltage signal for the MCU that varies with the oxygen content of the exhaust gas.

Thermal Electric Switch (TES)
This switch is mounted inside the air cleaner. When air temperature is below the calibrated value, the TES provides a ground circuit for the MCU to indicate the necessity for a cold weather engine start. When air temperature is above the calibrated value, the TES provides an open circuit to indicate a normal start.

Wide Open Throttle (WOT) Switch
This is a mechanically operated electrical switch controlled by throttle position to indicate a wide open throttle condition.

Coolant Temperature Switch
This is a dual function switch, controlled by engine coolant temperature. The switch is integral with the intake manifold heater control switch. When open, the switch indicates that the engine is cold.

4 Inches Hg. Vacuum Switch, Except 4-150
This switch is controlled by ported vacuum from the carburetor and has a normally closed electrical contact which indicates a closed throttle condition. The switch opens when vacuum drops below 4 inches Hg.

10 Inches Hg Vacuum Switch Except 4-150
This switch is controlled by manifold vacuum and opens when vacuum drops below 10 inches Hg, indicating a deep throttle condition.

4 Inches Hg Vacuum Switch, 4-150
This switch is controlled by ported vacuum and has a normally open electrical contact when vacuum level is less than 4 inches Hg. When vacuum level reaches or exceeds 4 inches Hg, the switch closes and indicates to the MCU when a closed or partial throttle occurs.

10 Inches Hg Vacuum Switch, 4-150
This switch is controlled by manifold vacuum and has a normally closed electrical contact when vacuum is less than 10 inches Hg. when vacuum level reaches or exceeds 10 inches Hg, the switch opens and indicates to the MCU when a part throttle or medium throttle condition occurs.

Closed Throttle Switch, 4-150
This switch is an integral part of the Sole-Vac throttle positioner and is attached to the vacuum actuator. When the throttle is in the closed position, this electrical switch indicates to the MCU a closed throttle position.

Distributor, 4-150 & 6-258
The MCU will advance or retard ignition timing as necessary for the proper engine operating condition according to tach voltage input provided by the distributor.

Knock Sensor
This sensor is a tuned piezoelectric crystal transducer located in the cylinder head. It provides an electrical signal to the MCU that is created by engine detonation. Vibration from engine knock produces an electrical signal through this sensor, which relays to the MCU to retard ignition timing of any single cylinder or any combination of cylinders, eliminating the knock condition.