Engine Control Module ECM

DTC 32 Chart:

DTC 32 Circuit:

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

DTC 32 Will Set When: The ECM monitors EGR effectiveness by de-energizing the EGR control solenoid; thereby, shutting "OFF" vacuum to the EGR valve diaphragm. With the EGR valve closed, and O2S fluctuating normally, short term fuel trim counts will be greater than they were during normal EGR operation. If the change is not within the calibrated window, a DTC 32 will be set.

The ECM will check EGR operation when:

^ Vehicle speed is above 45 mph.

^ Engine vacuum is between 15 and 60 kPa.

^ Throttle angle between 6 and 30%.

^ No change in throttle position while test is being run, max 4%.

^ EGR on threshold 98%.

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

DTC 32 Will Clear When: Conditions for fault are no longer present and Tech 1 "Clear DTCs" function is used or 50 ignition switch keycycles have passed with no further faults or ignition switch is turned "OFF" and ECM B fuse is removed for 10 seconds.

DTC Chart Test Description: Number(s) below refer to circled number(s) on the diagnostic chart.

1. By grounding the diagnostic terminal, the EGR solenoid should be energized and allow vacuum to be applied to the EGR valve, and the vacuum should hold.

2. The MIL should also flash while the diagnostic terminal is grounded. If the tight does not flash, this may indicate that the "quad-driver" has been damaged by low resistance in TCC circuit.

3. When the diagnostic terminal is ungrounded, the vacuum to the EGR valve should bleed off through a vent in the solenoid and the valve should close. The 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. This system uses a negative backpressure valve which should hold vacuum with engine "OFF."

6. When engine is started, exhaust backpressure should cause vacuum to bleed off and valve should fully close.

Diagnostic Aids:

^ Before replacing ECM, use an ohmmeter and check the resistance of each ISCM controlled relay and solenoid coil. For example: TCC, etc., refer to C Charts / ECM QDR Check Procedure. ECM QDR Check Procedure