EL Camino V6-262 4.3L (1985)
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 grounded 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 min. Coolant temperature above 80~C.
^
Vehicle speed above 5 mph.
^
Throttle off idle. TPS signal about .75 volt.
Test Description:
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 battery 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 function at check by grounding 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
"Quad-Drivers". Failure of one can damage any other driver within the set.
Solenoid coil resistance must measure more than 20 ohms. Less resistance will cause early failure of the ECM "DRIVER". Using an ohmmeter,
check the solenoid coil resistance of all ECM controlled solenoids and relays before installing a replacement ECM.
