K 3500 Truck 4WD V8-454 7.4L (1994)
Canister Purge Solenoid: Description and Operation
Canister Purge Solenoid
PURPOSE
The Canister Purge Solenoid is controlled by the PCM and allows manifold and/or ported vacuum to purge the fuel evaporative cannister when
energized.
OPERATION
The PCM operates a normally closed solenoid to control vacuum to purge the canister. Under cold engine or idle conditions, the solenoid is turned
"OFF" by the PCM, which blocks vacuum and prevents purge of the canister.
The PCM turns "ON" the solenoid valve and allows purge when the following conditions are met:
-
Engine coolant temperature above 113° F (45° C)
-
Short term fuel trim cell is less than 122 counts.
