Evaporative Emissions System: Testing and Inspection

Purge Valve Circuit Diagram:

CIRCUIT DESCRIPTION:
The canister purge is controlled by a solenoid that blocks vacuum to the fuel vapor canister when energized. The solenoid gets power when the ignition is turned "ON" and the PCM controls the ground circuit.

Purge Valve Checking (Chart C-3):

CANISTER PURGE VALVE CHECK

TEST DESCRIPTION: The numbers below refer to circled numbers on the diagnostic chart.

1. This checks to find if the solenoid valve is open or closed. The normally closed valve should be closed when not energized (no vacuum at gauge.)
2. This checks to see if the solenoid will operate properly when its ground circuit is completed. Vacuum should be present at the gauge when the solenoid is cycled "ON".

NOTE: Once the test sequence is completed, clear codes, operate vehicle, and check for recurring trouble codes.

DIAGNOSTIC AID

The canister purge solenoid is a normally closed solenoid valve. The valve is energized (open) when all the following conditions exist:

^ Engine running longer than 20 seconds w/engine at normal operating temperature (2.5 minutes after cold start).
^ Engine coolant temperature greater than 60°C (158°F)
^ Intake air temperature greater than 10°C (50°F).