Canister Purge Solenoid: Description and Operation

1997 DUTY CYCLE EVAP PURGE SOLENOID-PCM OUTPUT
The duty cycle EVAP purge solenoid regulates the rate of vapor flow from the EVAP canister to the throttle body. The Powertrain Control Module (PCM) operates the solenoid.

During the cold start warm-up period and the hot start time delay, the PCM does not energize the solenoid. When de-energized, no vapors are purged.

The engine enters closed loop operation after it reaches a specified temperature and the programmed time delay ends. During closed loop operation, the PCM energizes and de-energizes the solenoid 5 to 10 times per second, depending upon operating conditions. The PCM varies the vapor flow rate by changing solenoid pulse width. Pulse width is the amount of time the solenoid is energized.

Duty Cycle EVAP Purge Solenoid:

The EVAP purge solenoid and bracket attach to the right inner fender well next to the dash panel. The top of the solenoid has the word TOP on it. The solenoid will not operate unless it is installed correctly. If the vehicle has a 3.5L engine, the EVAP purge solenoid shares a bracket with the MTV solenoid.