Chart C-3 EVAP Canister Purge Valve Check

Chart C-3, Evaporative Canister Purge Valve Check:

EVAP Canister Purge Valve Circuit:

CIRCUIT DESCRIPTION
The canister purge solenoid is a normally closed vacuum solenoid valve that opens when energized, allowing the fuel vapors stored in the canister to be consumed in the engine. The solenoid gets battery power when the ignition is turned and becomes energized (purge "ON") when the PCM completes the circuit to ground. Purge is regulated by operating the solenoid on a duty cycle ("ON" time vs. "OFF" time.) Duty cycle is varied from 0% (purge "OFF") to 100% (purge "ON" full), depending on operating conditions.

The purge solenoid is energized (purge "ON") when:
^ The DLC diagnostic EVAP request terminal is grounded with the engine stopped.

Or

^ Engine run time after start more than 20 seconds on a warm engine or 2.5 minutes on a cold engine.
^ Engine coolant temperature above 60°C (158°F).
^ Intake Air Temperature (IAT) sensor indicates temperature above 9.5°C (50°F).


TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. Checks to see if the solenoid is opened or closed. The solenoid is normally de-energized in this step (should be closed.)
2. Completes functional check. This should normally energize the solenoid and allow vacuum to the gage (purge "ON").


DIAGNOSTIC AIDS
^ Inspect the canister for cracks or fuel saturation.
^ Inspect fuel vapor lines from the fuel tank or intake for leaks, being disconnected or sharp bends blocking the flow of vapors.