Chart C-3 Canister Purge Check

Chart C-3 "Canister Purge Solenoid Diagnosis":

Wiring Diagram - Canister Purge Solenod:

CHART C-3

CANISTER PURGE SOLENOID DIAGNOSIS


Circuit Description:

Canister purge is controlled by a normally closed solenoid that allows manifold vacuum to purge the canister when energized. The ECM supplies a ground to energize the solenoid (purge "ON"). Electrical circuit problems should result in Code 31 being set and the Code 31 chart should be used for diagnosis. This chart provides a functional check of the system.


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 de-energized in this step, so it should be closed.

2. Completes functional check by grounding test terminal. This should normally energize the solenoid and allow the vacuum to drop (purge "ON").

3. Checks for open or shorted solenoid circuit.

4. Checks to see if ECM control circuit or solenoid is at fault. Solenoid coil resistance must measure more than 20 ohms. Less resistance will cause the CCP driver to open within the ECM as all QDRs are fault protected.


5. If the test light goes "OFF" with the ECM disconnected, the quad-driver within the ECM is faulty and the ECM has to be replaced.

Diagnostic Aids

The CCP driver is a QDR which is "protected." This means it will turn "OFF" if too much current flows into terminal "17". This would result from a shorted canister purge solenoid or a short to voltage on CKT 428, and would cause terminal "17" voltage to be high even with purge commanded "ON." Low voltage at terminal "17" with purge "OFF" would result from an open from B+.


**EMI