Turbocharger: Description and Operation

Turbocharger Control System (TCS):

The Turbocharger Control System (TCS) is controlled by a TCS control unit and the ECM. A stepping motor is utilized to open and close the turbo wastegate and thus regulate boost pressure. The motor can rotate 90° by pulses received from the TCS control unit. A microswitch tells the TCS control unit when the motor is at 0° and 250 pulses are required to move the motor through its range of travel.

To calculate boost pressure, the TCS control unit utilizes inputs from a coolant temperature sensor, the ignition coil (engine rpm) and the throttle position sensor. The ECM sends the knock sensor signal to the TCS control unit, enabling it to use that input as well for calculating boost pressure.

TCS Self-Diagnosis:

The turbocharger control system has a self-diagnostic capability. Various system problems will set trouble codes which can be read from a flashing LED display on the TCS control unit.

LED flashes Problem detected

1 Knock control circuit
2 Ignition signal circuit
3 Coolant sensor circuit
4 Stepping motor circuit
5 Throttle sensor circuit
6 Throttle sensor circuit
7 Power supply voltage