DTC 32

Flowchart Code 32:

Exhaust Gas Recirculation (EGR) Circuit:

*** UPDATED BY TSB #88-167-6E, March 1988 ***

CIRCUIT DESCRIPTION
The integrated electronic Exhaust Gas Recirculation (EGR) valve functions similar to a port EGR valve with a remote vacuum regulator. The internal solenoid is normally open, which causes the vacuum signal to be vented "OFF" to the atmosphere when EGR is not being commanded by the Electronic Control Module (ECM). This EGR valve has a sealed cap and the solenoid valve opens and closes the vacuum signal which controls the amount of vacuum vented to atmosphere, and this controls the amount of vacuum applied to the diaphragm.

The electronic EGR valve contains a voltage regulator which converts the ECM signal to provide different amounts of EGR flow by regulating the ECM controls EGR flow with a pulse width modulated signal (turns "ON" and "OFF" may times a second) based on air flow, Throttle Position Sensor (TPS) and rpm. This system also contains a pintle position sensor which works similar to a TPS sensor and as EGR now is increased, the sensor output also increases. Code 32 means that there has been an EGR system fault detected. Code 32 will set under two conditions:

^ Coolant temperature above a specified amount, EGR should be "ON"
^ EGR pintle position does not match duty cycle.

TEST DESCRIPTION
Numbers below refer to circles numbers on the diagnostic chart.

1. Whenever the internal solenoid is de-energized, the solenoid valve should be closed which should not allow the vacuum to move the EGR diaphragm. However, if the filter is plugged, the vacuum applied with the hand held vacuum pump will cause the diaphragm to move because the vacuum will not be vented to the atmosphere.

2. Grounding the diagnostic terminal should energize the internal solenoid which closes off the vent and allows the vacuum to move the diaphragm. This test determines that the ECM is capable of controlling the solenoid. When EGR is commanded on by the ECM, the test light should be "ON".

3. If Circuit (CKT) 450 is open, the pintle signal will go high (showing a 5 volt signal). This will set a Code 32. If CKT 911 becomes shorted to 12 volts or CKT 474, the signal voltage will go high causing a Code 32.

DIAGNOSTIC AIDS
Some "Scan" tools will read pintle position in volts. The EGR position voltage can be used to determine that the pintle is moving. When no EGR is commanded (0% duty cycle), the position sensor should read between 0.5 volt and 1.5 volts and increase with the commanded EGR duty cycle.