Canister Purge Control Valve: Testing and Inspection

Chart C-3, Canister Purge Solenoid Valve Check:

Purge Solenoid Circuit Diagram:

CIRCUIT DESCRIPTION
Canister purge is controlled by a solenoid that allows manifold vacuum to purge the fuel vapor canister when energized. The purge solenoid is a normally closed solenoid valve that gets battery power when the ignition is "ON" and becomes energized when the ECM completes the circuit to ground. If the diagnostic "test" terminal is grounded with the engine stopped and ignition "ON", or the following conditions are met with the engine running, the purge solenoid will be energized (purge "ON").

^ Coolant temperature sensor indicates engine temperature greater than 65°C (149°F).
^ Vehicle speed sensor indicates speed greater than 10 mph.
^ Throttle position sensor signal indicates throttle opening greater than 3.5%.
^ System is not in decel fuel cut-off mode.
^ System is in "closed loop" operation.
OR
^ with the ignition "ON" and engine not running, grounding the diagnostic test terminal will cause the ECM to energize the solenoid, for testing (see step 2 in test description.)

TEST DESCRIPTION
Numbers below refer to circled numbers on the diagnostic chart.
1. Checks to see if the solenoid is opened or closed. The solenoid is normally closed and should open when the diagnostic test terminal is grounded.
2. Completes functional check by grounding the diagnostic "test" terminal. This should energize the solenoid and allow the vacuum to drop (purge "ON").
3. If fuse is OK, carefully check all circuitry for obvious problems before removing intake plenum for the next step.
4. Refer to wiring diagrams in ELECTRICAL WIRING AND TROUBLE SHOOTING. The "ENG 1" fuse also provides electrical power to the following devices:

2nd - 3rd block-our relay
Throttle position sensor module
Camshaft sensor
Ignition module
Secondary port throttle valve solenoid

If the fuse is burned out, check these other circuits also for shorts to ground.

DIAGNOSTIC AIDS
Normally, the canister purge solenoid is "OFF" (closed) and should only energize under the conditions described above.