Canister Purge Solenoid

*** THIS ARTICLE INCLUDES REVISIONS MADE BY TSB #516563, DATED OCTOBER 1995 ***

EVAP Canister Purge Solenoid Check:

GENERAL DESCRIPTION
This Evaporative Emissions System (EVAP) system uses an electrically controlled solenoid to purge fuel vapor from the EVAP canister to the intake manifold. The control module cycles the solenoid, once the engine coolant has reached normal operating temperature.

CIRCUIT DESCRIPTION
B+ is applied to the EVAP Canister Purge Solenoid when the ignition key is turned "ON." Once the engine coolant has reached normal operating temperature, the control module grounds the EVAP Canister Purge Control circuit. The purge solenoid will open, allowing the fuel vapors from the vapor canister to be directed to the intake manifold.

CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.

1. Checks to see if a vacuum source is present, along with certain conditions before the EVAP canister purge solenoid is commanded "ON." Also shows a change of vacuum as EVAP canister purge solenoid is being cycled.
2. Checks for power to the EVAP canister purge solenoid, the ground circuit, the connections at the EVAP canister purge solenoid and the EVAP canister purge solenoid itself.
3. Checks for open or grounded Circuit (CKT) 539.
4. Checks for open CKT 428 or faulty control module.