EVAP Purge Solenoid Circuit

NAME OF CODE:
EVAP Solenoid Circuit

WHEN MONITORED:
With the ignition key ON and the engine running.

SET CONDITION:
When de-energized the valve routes manifold vacuum to a vacuum operated valve on the evaporative emissions canister to open it. with the vacuum valve opened, throttle body and/or manifold vacuum is used to purge the fuel vapors from the canister. The solenoid coil has resistance of 45 ohms and requires 8 volts to pull in and will remain pulled in while the voltage is above 1.5 volts.

THEORY OF OPERATION:
The PCM enables the EVAP after the engine reaches operating temperature. The evap corruption check cycle, which lasts a maximum of 12 seconds, is the only time that purge is disabled. At closed throttle, all fuel vapors are purged to the intake manifold. Increases in throttle opening, which result in increased vacuum above the throttle blade, result in a proportionate increase in the flow of fuel vapors to the throttle body port. The purging of vapors through the throttle body and the intake manifold is known as "bi-level purge". This solenoid has one side of its coil connected to ignition. To energize this solenoid, the PCM through the SPI-O supplies a sink to ground. A capacitor is used to shunt transients to ground. This output is monitored for diagnostic purposes.

POSSIBLE CAUSES:
- Open or shorted control circuit
- Open fused ignition switch output circuit
- Open or shorted solenoid control coil
- PCM failure
- Connector terminals
- Connector wires