Canister Purge Control Valve: Testing and Inspection

Canister Purge Solenoid Check Chart C-3:

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 solenoid 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").

^ Engine run time after start more than 1 minute
^ Coolant temperature above 60°C (140°F)
^ Vehicle speed above 2 mph
^ Throttle off idle, above 3%
^ IAT is less than 105°C (221°F)


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. Checks for a complete circuit. Normally, there is ignition voltage on CKT 339 and the ECM provides a ground on CKT 428. A shorted solenoid could cause an open circuit in the ECM (ECM fault).

Diagnostic Aids
Normal operation of the canister purge solenoid described as follows:

^ With the ignition "ON", engine "OFF", diagnostic "test" terminal grounded, the canister purge solenoid should be energized.