Circuit/System Description

The engine control module (ECM) performs the turbocharger (TC) learn procedure automatically when the enabling criteria have been met. After each ignition cycle, and before the enable criteria have been met, the ECM will use the previously learned value. If the ECM does not have a previously learned value, it will default to a stored calibrated value.

The ECM commands the TC vane control solenoid to position the TC vanes, and a TC vane position sensor monitors the actual position of the vanes. The ECM varies the boost dependant upon the load requirements of the engine.

The vane control solenoid has 2 circuits; a high voltage control circuit and a low voltage control circuit. The ECM uses a pulse width modulation (PWM) on both circuits to control the solenoid.

The TC Learn can also detect sticking vanes, sticking control solenoid, or position sensor errors. During the TC Learn, the ECM commands the vanes to 0 percent, then to 100 percent, while comparing the actual and desired TC vane position values. If the difference between the values is greater than or less than, a calibrated threshold, the automatic learn fails.