Ciera Cruiser V6-173 2.8L VIN W FI (1986)
Wiring Diagram for Chart C-3 - Canister Purge Check
CHART C-3 - CANISTER PURGE CHECK
Circuit Description:
Canister purge is controlled by a solenoid that allows manifold vacuum to purge the canister when de-energized. The ECM supplies a ground to energize
the solenoid (purge "OFF").
If the diagnostic "test" terminal is ungrounded with the engine stopped or the following is met with the engine running the purge solenoid is de-energized
(purge "ON").
^
Engine run time after start more than 1 minute
^
Coolant temperature above 75~C
^
Vehicle speed above 15 mph
^
Throttle "OFF" idle
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 energized in this step; so it should be closed.
2.
Checks for a complete circuit. Normally there is ignition voltage on CKT 39 and the ECM provides a ground on CKT 428. A shorted solenoid
could cause an open circuit in the ECM.
3.
Completes functional check by ungrounding "test" terminal. This should normally de-energize the solenoid and allow the vacuum to drop (purge
"ON").
4.
Solenoids or relays are turned "ON" or OFF" by the ECM internal electronic switches called "drivers." Each driver is part of a group of four called
quad-drivers. Failure of one can damage any other driver within the set. See CHART C-1.
