Canister Purge Solenoid: Description and Operation

Fig. 8 EVAP Purge Solenoid Valve Location:

EVAP Purge Solenoid:

NOTE: The duty cycle EVAP purge solenoid is mounted on the side of the air cleaner. The top of the solenoid has the word TOP on it. The solenoid will not operate unless it is installed correctly.

FUNCTION
The Duty Cycle EVAP Purge solenoid controls the rate of vapor flow from charcoal canister to the throttle body. The PCM regulates purge solenoid operation.

OPERATION
The PCM controls purge solenoid by switching the ground path on and off based on engine operating conditions. When solenoid is energized, vacuum is prevented from reaching the charcoal canister. When solenoid is de-energized, vacuum is allowed to reach the charcoal canister. The PCM energizes and de-energizes the solenoid 5 to 10 times per second. The PCM controls the rater of flow by adjusting solenoid pulse width.

CONDITIONS
The PCM will not allow vapors to be purged until the engine has reached a predetermined temperature and a time delay interval has elapsed. The PCM, under certain idle conditions, energizes the solenoid to update fuel calibration.

CIRCUIT OPERATION
Circuit F18 supplies battery voltage to the duty cycle EVAP/Purge solenoid. This circuit is HOT in the START and RUN position only. It is also spliced and provides power for the A/C clutch relay, exhaust gas recirculation solenoid, Manifold Tuning Valve (MTV) solenoid, and the radiator fan relays.

Circuit F18 connects to the junction block, cavity 20, and is protected by a 10 Amp fuse. Power for the fuse is supplied on circuit A21 from the ignition switch. Circuit A1 provides power for the A21 circuit and is protected by a 20 Amp fuse located in cavity A of the Power Distribution Center (PDC).

The Powertrain Control Module (PCM) controls the ground path for the solenoid on circuit K52. Circuit K52 connects to cavity 68 of the PCM connector.