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Code Chart 32:

EGR Valve Solenoid Circuit:

CIRCUIT DESCRIPTION:
The Exhaust Gas Recirculation (EGR) system is controlled by the ECM. The ECM controls the vacuum being supplied to the valve by energizing and de-energizing a solenoid. The ECM uses information from various engine sensors to determine when EGR is necessary. Once the ECM has requested EGR by grounding the solenoid circuit, the ECM will monitor engine operating conditions to determine if exhaust gas flow has entered the intake manifold. When the ECM tests for EGR operation and no change in engine operating conditions is indicated, a DTC 32 will set.

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

1. Intake passage: shut "OFF" engine and remove the EGR valve from the manifold. Plug the exhaust side hole with a suitable stopper. Leaving the intake side hole open, attempt to start the engine. If the engine runs at a high idle (up to 3000 rpm is possible) or starts and stalls, the EGR intake passage is not restricted. If the engine starts and idles normally, the EGR intake passage is restricted.
Exhaust Passage: With EGR valve still removed, plug the intake side hole with a suitable stopper. With the exhaust side hole open, start engine and check for the presence of exhaust gas. If no exhaust gas is present, the EGR exhaust side passage is restricted.

2. By grounding the diagnostic test terminal, the EGR solenoid should be energized and allow vacuum to be applied to the gauge. The vacuum at the gauge may or may not slowly bleed off. It is important that the gauge is able to read the amount of vacuum being applied.

3. When the diagnostic test terminal is ungrounded, the vacuum gauge should bleed off completely through a vent in the solenoid. The vacuum pump gauge may or may not bleed off, but this does not indicate a problem.

4. This test will determine if the electrical control part of the system is at fault or if the connector of or solenoid is at fault.

5. At this point, it has been determined that the EGR solenoid, the ECM, and the vacuum supply are OK.

DIAGNOSTIC AIDS:
Vacuum lines should be thoroughly checked for proper routing. Refer to vehicle emission control information label. Suction from shop exhaust hoses can alter backpressure and may affect the functional check of the EGR valve.

If the EGR system is found to be functioning correctly and DTC 32 is set, low fuel pressure or lean fuel injectors could be the cause of setting DTC 32. It may be necessary to monitor fuel pressure while driving the vehicle at various road speeds and/or loads. Related Tests, Information and Procedures Chart C-2A Fuel Injector Balance Test