Component Functional Description - Purge Solenoid

Functional Operation:  The normally closed Purge Solenoid is energized to open and allow the fuel vapors to be drawn from the Charcoal Canister into the engine. The solenoid has one inlet port that connects to the canister and one outlet port that connects to the Intake Manifold. Once in closed loop the Purge Solenoid is controlled using a Pulse Width Modulated (PWM) control circuit. The normally closed Purge Solenoid will open and allow engine vacuum from the Intake Manifold to draw vapors from the Charcoal Canister into the Intake Manifold to be burned by the engine. The PCM varies the vapor flow rate by changing the duty cycle on the purge solenoid control circuit. The PCM adjusts the pulse width of the Purge Solenoid based on engine operating conditions.

Diagnostic Overview:  The Powertrain Control Module (PCM) performs circuit fault diagnostics on the Purge Solenoid control circuitry for open or short circuits. The PCM can also detect a stuck closed Purge Solenoid using the Purge Flow Monitor diagnostic. The Purge Solenoid functionality can be tested using a hand vacuum pump.

• With the Purge Solenoid de-energized, connect the hand vacuum pump to the outlet port for the Intake Manifold and apply approximately 10 - 15 in. Hg. The solenoid should hold the vacuum if the Purge Solenoid is closed.
• To verify the Purge Solenoid is not stuck closed, energize the solenoid to open it with vacuum applied at the outlet port. The vacuum should disappear when the solenoid is energized.