Circuit/System Description

WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The engine control module (ECM) performs the turbocharger (TC) learn procedure automatically when the enabling criteria's 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 learn value, it will default to a stored calibrated value.

The ECM performs the self learn by commanding the TC vanes to 0 percent, then to 100 percent, while monitoring the TC vane position sensor.

The ECM utilizes a TC vane control solenoid and a TC vane position sensor to control the TC vanes. The ECM will vary the boost dependant upon the load requirements of the engine. The vane control solenoid has a high voltage control circuit and a low voltage control circuit. The ECM uses a pulse width modulation (PWM) on the high control and low control circuits to control the solenoid. The ECM will detect if the automatic TC learn has failed if the commanded vane position did not match the actual vane position by a calibrated threshold.