Grand Caravan FWD V6-3.0L VIN 3 (1999)
Canister Purge Solenoid: Description and Operation
Proportion Purge Solenoid
OPERATION
All vehicles use a proportional purge solenoid. The solenoid regulates the rate of vapor flow from the EVAP canister to the throttle body. The
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 proportional purge solenoid operates at a frequency of 200 hz and is controlled by an engine controller circuit that senses the current being
applied to the proportional purge solenoid and then adjusts that current to achieve the desired purge flow. The proportional purge solenoid
controls the purge rate of fuel vapors from the vapor canister and fuel tank to the engine intake manifold.
DUTY CYCLE EVAP CANISTER 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 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 PCM de-energizes the solenoid during open loop operation.
The engine enters closed loop operation after it reaches a specified temperature and the time delay ends. During closed loop operation, the PCM
energizes and de-energizes the solenoid 5 or 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 energizes.
