Throttle Motor And Feedback Position

MDK:  The MS42 ECM powers the MDK motor using pulse width modulation for opening and closing at a basic frequency of 600 Hz which positions the throttle plate. The throttle plate is also closed by an integrated return spring.

Dual potentiometers feedback the actual throttle plate position, allowing the ECM to verify correct throttle position. Dual potentiometers are used for feedback plausibility.

EDK:  The MS43 ECM powers the EDK motor using pulse width modulation for opening and closing the throttle plate. The throttle plate is also closed by an integrated return spring.

Two integrated potentiometers provide voltage feedback signals to the ECM as the throttle plate is opened and closed.

• Feedback signal 1 provides a signal from 0.5v (closed) to 4.5 V (full throttle). 
• Feedback signal 2 provides a signal from 4.5v (closed) to 0.5 V (Full Throttle). 

Potentiometer 1 is the primary feedback signal of throttle plate position and signal 2 is the plausibility cross check through the complete throttle plate movement.

Idle Air Actuator:  This valve regulates air by-passing the throttle valve to control the engine idle/low speed.

The valve is supplied with battery voltage from the ECM Relay. The Idle Air Actuator is a two-coil rotary actuator. The ECM is equipped with two final stage transistors which will alternate positioning of the actuator.

The final stages are "pulsed" simultaneously by the ECM which provides ground paths for the actuator. The duty cycle of each circuit is varied to achieve the required idle RPM.

If this component/circuits are defective, a fault code will be set and the "Malfunction Indicator Light" will be illuminated when the OBD II criteria is achieved.

Hot-Film Air Mass Meter (HFM):  The air volume input signal is produced electronically by the HFM which uses a heated metal film (180°C above intake air temperature) in the air flow stream.

The ECM Relay provides the operating voltage. As air flows through the HFM, the film is cooled changing the resistance which affects current flow through the circuit. The sensor produces a 1-5 volt varying signal. Based on this change the ECM monitors and regulates the amount of injected fuel.

If this input is defective, a fault code will be set and the "Malfunction Indicator Light" will be illuminated when the OBD II criteria is achieved. The ECM will operate the engine using the Throttle Position and Engine RPM inputs.