California Emissions (Gen-IIS)

EGR Valve Check Procedure (Chart C-7):

EGR Control Wiring:

CIRCUIT DESCRIPTION
The digital Exhaust Gas Recirculation (EGR) valve is designed to accurately supply EGR to an engine independent of intake manifold vacuum. The valve controls EGR flow from the exhaust to the intake manifold through three orifices which increment in size to produce seven combinations. When a solenoid is energized, the armature, with attached shaft and swivel pintle is lifted, opening the orifice.

The flow accuracy is dependent on metering orifice size only, which results in improved control.

TEST DESCRIPTION
Numbers below refer to circled numbers on diagnostic chart.

1. Always check for trouble codes before attempting diagnosis of the EGR system. If there are codes present, correct these first.

2. This step activates each solenoid individually. As you energize #1 or #2 solenoid, the engine RPM should drop. #3 solenoid has the largest port and may stall the engine when energized.

DIAGNOSTIC NOTES:
If the digital EGR valve shows signs of excessive heat (a melted condition), check the exhaust system for blockage (possibly a plugged converter). One possibility is an injector stuck open.


EGR solenoids can be cycled "ON" and "OFF" manually by using the following supplemental procedure:

1. Instead of using a "SCAN" tool, start engine and disconnect EGR solenoid harness connector.
2. With engine idling, connect fused battery power (12 volts) to terminal "D" of solenoid valve assembly.
3. Ground terminal "C" of solenoid valve assembly (energizes solenoid #1).
^ You should notice a change in engine speed. If not check EGR passages for restriction. If passages are OK, replace EGR valve.
4. Ground terminal "E" of solenoid valve assembly (energizes solenoid #2).
^ You should notice a change in engine speed. If not, check EGR passages for restriction. If passages are OK, replace EGR valve.
5. Ground terminal "B" of solenoid valve assembly (energizes solenoid #3).
^ You should notice a change in engine speed and the engine may stumble and die. If not, check EGR passages for restriction. If passages are OK, replace EGR valve.

When testing is complete, clear trouble codes (you should have generated a code 33 if you performed test without a "SCAN" tool). Operate vehicle, then re-check to make sure there are no recuring codes.