Part 1 of 3

DTC 32 Chart Part 1 Of 3:

Wiring Diagram:

MAP With Key On Engine Off:

CIRCUIT DESCRIPTION:

The ECM operates a solenoid valve to control the Exhaust Gas Recirculation (EGR) valve. This solenoid valve is normally closed. By providing a ground path, the ECM energizes the solenoid valve which then allows vacuum to pass to the EGR valve.

The ECM monitors EGR effectiveness by de-energizing the EGR control solenoid valve, thereby, shutting "OFF" vacuum to the EGR valve diaphragm. With the EGR valve closed, manifold vacuum will be greater than it was during normal EGR operation and this change will be relayed to the ECM by the MAP sensor. If the vacuum change is not within the calibrated window, a DTC 32 will be set.

The ECM will check EGR operation when:

^ Vehicle speed is above 80 km/h (50 mph).
^ MAP is as listed in table (depends on altitude).
^ TP is between 9% and 20% (5.OL & 5.7L).
^ TP is between 5% and 20% (4.3L).
^ No change in Throttle Position (TP) while test is being run.

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


1. Intake Passage: Shut "OFF" the engine and remove the EGR valve from the manifold. Plug the exhaust side hole with a shop towel or suitable stopper. Leaving the intake hole open, attempt to start the engine. If the engine runs at a very high idle speed (up to 3000 rpm is possible) or starts and stalls, the EGR passages are not restricted. If the engine starts and idles normal, the EGR intake side passage, in the intake manifold, is restricted.
Exhaust Passage: With the EGR valve still removed, plug the intake side hole with the same stopper. With the exhaust side hole open, check for the presence of exhaust gas. If no exhaust gas is present, the EGR exhaust side passage, in the intake manifold, is restricted.
NOTE: Remove towel or stopper once test is complete.

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

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

4. This test determines if the electrical control portion of the system is at fault, or if the EGR solenoid and/or connector is at fault.

5. EGR valves used with this engine are stamped "P" for Positive and "N" for Negative. See EMISSION CONTROLS, for "EGR IDENTIFICATION," under COMPONENT OPERATION, to assist in determining the type of EGR valve used.



DIAGNOSTIC AIDS:


^ Vacuum lines should be thoroughly checked for proper routing. Vacuum source goes to the oriice side of the EGR valve. Refer to Vehicle Emission Control Information" label.

^ Suction from shop exhaust hoses can alter exhaust backpressure and may affect the functional check of the EGR system.