With 4L80E Automatic Transmission

Exhaust Gas Recirculation System Circuit Code 32:

Exhaust Gas Recirculation System Circuit:

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

The PCM 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 PCM will check EGR operation when:
^ Engine speed is greater than 1600 rpm.
^ Engine vacuum is between 20 and 60 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. Energizing the solenoid will allow vacuum to pass to the valve.

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

3. 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 PCM is commanding the system "ON."


Diagnostic Aids:
Before replacing PCM, use an ohmmeter and check the resistance of each PCM controlled relay and solenoid coil.

Refer to "PCM 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. The EVRV solenoid cannot be diagnosed by a electrical check, because of the solid state circuitry involved.