MI-04 SECM (Load/Speed Management) Drive by wire refers to the fact that the MI-04 control system has no throttle cable from the Acceleration Pedal (Figure 26) to the throttle body. Instead, the SECM is electronically connected both to the Acceleration Pedal assembly and the throttle body. The SECM monitors the Acceleration Pedal position and controls the throttle plate by driving a dc motor connected to the throttle. The dc motor actuates the throttle plate to correspond to the Acceleration Pedal position when the operator depresses the pedal.
The use of electronic throttle control (ETC) ensures that the engine only receives the correct amount of throttle opening for any given situation, greatly improving idle quality and drivability. A Throttle Position Sensor (TPS), (Figure 27) which is integral to the Drive By Wire (DBW) throttle assembly, provides feedback for position control by monitoring the exact position of the throttle valve. NOTE The DV-E5 is not a serviceable assembly. If the TPS sensor fails, the assembly should be replaced. SECM self-calibration and “cross checking” of the TPS is accomplished by comparing the TPS signal to a calculated throttle position in the SECM software (Predicted TPS).
In addition to the throttle position sensor, a Temperature/Manifold Air Pressure Sensor (TMAP) is used to monitor intake manifold temperature and pressure (Figure 28). This enables the SECM full control capabilities monitoring actual airflow in relationship to desired airflow. The TMAP sensor is a single unit incorporating both intake manifold temperature and manifold pressure measurement. Figure 27 Figure 26 Figure 28 G420E/G424E Tier LP Engine System Operational Overview 27