DTC 32

DTC 32 Exhaust Gas Recirculation System Failure:

CHART 1 OF 2

DTC 32 Exhaust Gas Recirculation System Failure (Part 2 Of 2):

CHART 2 OF 2

EGR Solenoid Wiring 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 as flow has entered the intake manifold.

DTC 32 Will Set When:
^ Long term fuel trim is in fuel trim cell 2 (cruise condition at approximately 55 mph).
^ No DTC 21 or DTC 33.
^ The difference between the two long term fuel trim values is greater than 12 and the long term fuel trim value in fuel trim cell 2 is greater than 140.
^ The ECM tests for EGR operation and no change in engine operating conditions is indicated.

Action Taken (ECM will default to): Malfunction Indicator Lamp (MIL) illuminates.

DTC Chart Test Description: Number(s) below refer to circled number(s) 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 the 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 gage. The vacuum at the gage may or may not slowly bleed off. It is important that the gage is able to read the amount of vacuum being applied.
3. When the diagnostic "test" terminal is ungrounded, the vacuum gage should bleed off completely through a vent in the solenoid.
The vacuum pump gage 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 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.
6. The remaining tests check the ability of the EGR valve to interact with the exhaust system. This system uses a positive backpressure EGR valve which will not hold vacuum until sufficient exhaust backpressure is at the base of the valve.
7. The EGR valve diaphragm should move when sufficient exhaust backpressure is present at the base of the valve and when vacuum is being supplied to the valve. Rapidly "snapping" the throttle from idle should provide sufficient exhaust backpressure to the base of the valve which will close an internal vacuum bleed. With the EGR valve's internal vacuum bleed closed the "jumpered" vacuum supply can now lift the valve off its seat. The amount of valve pintle movement will be small. It is important that the valve pintle moves at the proper time.
8. Excessive exhaust backpressure from bent or restricted exhaust system components could provide enough backpressure at the base of the EGR valve to close the valve's internal bleed and allow undesired EGR valve operation at idle.
9. Plugged EGR exhaust passages can block exhaust backpressure from reaching the EGR valve. With no EGR exhaust backpressure at the base of the valve, the valve's internal bleed will remain open and prevent vacuum from operating the valve.

Diagnostic Aids:
Vacuum lines should be thoroughly checked for proper routing. Refer to "Vehicle Emission Control Information" label.

If the EGR system is found to be functioning correctly and DTC 32 is set low fuel pressure or lean fuel injector(s) 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. Refer to CHART A-7. Related Tests, Information and Procedures Perform the "Injector Balance Test" in "Fuel Delivery System," CHART C2-A. Chart C-2A Injector Coil Test Procedure

NOTICE: Suction from shop exhaust hoses can alter backpressure and may affect the functional check of the EGR valve.