DTC P0443: EVAP Purge Solenoid Control Circuit: Description

WARNING: This page is about a different car, the 2001 GMC Savana, 2001 Chevrolet RV Cutaway, 2001 Chevrolet Cutaway, and 2001 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.

Evaporative emission (EVAP) solenoid valve is Pulse Width Modulated (PWM). Powertrain Control Module (PCM) controls EVAP canister purge solenoid valve duty cycle by controlling amount of purge valve solenoid on time. Scan tool displays amount of on time in percentage. This value is the amount of available vacuum that is applied to EVAP system. Ignition voltage is supplied directly to EVAP canister purge valve. PCM controls solenoid by grounding control circuit via an internal switch called a driver. Primary function of driver is to supply ground for controlled component. Each driver has a fault line which PCM monitors. Voltage of control circuit should be low, about zero volts, when PCM commands a component on. Voltage potential of circuit should be high, about battery voltage, when PCM commands control circuit to a component off. If fault detection circuit senses a voltage other than what PCM expects, fault line status changes causing DTC P0443 to set.