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Home >> GMC >> 2002 >> C3500 HD 6.5 F, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - 6.5L >> Diagnostic Information and Procedures >> DTC P1656 >> Circuit Description

Circuit Description

The turbocharger wastegate is a vacuum actuated valve used to control the exhaust gas heat sent to the turbo. The wastegate pulse width modulated solenoid meters the vacuum level at the wastegate valve actuator as commanded by the PCM. When the PCM is commanding the wastegate solenoid ON, the voltage potential of the circuit will be low (near 0 volts). When the PCM is commanding the wastegate solenoid OFF, the voltage potential of the circuit will be high (near battery voltage). The primary function of the PCM in this circuit is to supply the ground for the wastegate solenoid.