Chart C-3 Evaporative Emission Control System

Chart C-3:

Wiring Diagram:

CIRCUIT DESCRIPTION:

The canister purge is controlled by a solenoid that allows vacuum to purge the fuel vapor canister when energized. The ECM controls the ground to power the solenoid. If the diagnostic test terminal is grounded with the engine not running, or the following conditions exists with the engine running, the purge solenoid is energized (purge "ON").

^ The engine run time is more than 30 seconds.
^ The coolant temperature is above 63°C (145°F).
^ Vehicle speed is above 5 mph.

NOTE: Because of all the possible color code combinations used on electrical wiring diagrams, always refer to SCHEMATIC DIAGRAMS/ELECTRICAL AND ELECTRONIC WIRING DIAGRAMS/ECM CONNECTOR IDENTIFICATION for correct color code identification of circuit.

TEST DESCRIPTION: The numbers below refer to circled numbers on the diagnostic chart.

1. This checks to see if the solenoid is opened or closed. It should be closed (de-energized).

2. This completes a functional check by grounding the test terminal. This should normally energize the solenoid and allow the vacuum to drop.

3. This checks for an open in circuits 428 or 639.