Evaporative Emission Operation Check (C-3)

Canister Purge Solenoid Circuit:

Chart C-3 Canister Purge Valve Check:

Circuit Description
Evaporate emission canister purge is controlled by a solenoid that allows manifold and/or ported vacuum to purge the canister when energized. The Engine Control Module (ECM) supplies a ground to energize the solenoid (purge "ON"). The purge solenoid control by the ECM is turned "ON" or "OFF" under specific engine conditions. The purge solenoid is turned "ON" when all of the following conditions are met.
^ Data link connector is ungrounded.
^ Engine run time after start more than 20 seconds.
^ Engine coolant temperature above 60'C.
^ Vehicle speed is above 9 miles per hour.
Also, if the diagnostic test terminal is grounded with the engine stopped, the purge solenoid is energized (purge "ON").

Test Description
Numbers below refer to circled number's on the diagnostic chart.
1. Check to see if the solenoid is opened or closed. The solenoid is normally de-energized in this step, so it should be closed.
2. Checks to determine if solenoid was open due to electrical CKT problem or defective solenoid.
3. Completes functional check by grounding test terminal. This should normally energize the solenoid opening the valve which should allow the vacuum to drop (purge "ON").

Diagnostic Aids
Make a visual check of vacuum hose(s). Check throttle body for possible cracked, or plugged vacuum block. Malfunction indicator lamp for possible mechanical problem.