Powertrain Controls - ECM/PCM

Exhaust Gas Recirculation System Circuit Code 32:

Exhaust Gas Recirculation System Circuit:

Circuit Description:
The ECM operates a EVRV solenoid, which is pulse width modulated EGR control, to control the Exhaust a 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.

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 O2 sensor fluctuating normally, fuel integrator counts will be greater than they were during normal EGR operation. If the change is not within the calibrated window, a Code 32 will be set. The ECM will check EGR operation when:

^ Vehicle speed is above 50 mph.
^ Engine vacuum is between 12.5 and 55 kPa.
^ No change in throttle position while test is being run.

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

1. With the ignition "ON," engine stopped, the solenoid should not be energized and vacuum should not pass to the EGR valve. Grounding the diagnostic terminal will energize the solenoid and allow vacuum to pass to valve.

2. Checks for plugged EGR passages. If passages are plugged, the engine may have severe detonation on acceleration.

3. The "Service Engine Soon" light should also flash while the diagnostic terminal is grounded. If the light does not flash, this may indicate that the "Quad-Driver" has been damaged by low resistance in the TCC circuit.

4. The vehicle must be driven during this test in order to produce sufficient engine load to operate the EGR. Lightly accelerating (approximately 1/4 throttle) will produce a large and stable enough reading to determine if the ECM is commanding the system "ON."


Diagnostic Aids:
Before replacing ECM, use an ohmmeter and check the resistance of each ECM controlled relay and solenoid coil. For example: TCC, except for the EVRV solenoid which cannot be diagnosed by a electrical check, because of the solid state circuitry involved, Refer to "ECM Wiring Diagram" for coil terminal identification of solenoid(s) and relay(s) to be checked. Replace any solenoid where resistance measures less than 20 ohms.