Part 2 of 2

DTC 32 Exhaust Gas Recirculation Circuit (Part 2 Of 2):

Exhaust Gas Recirculation (EGR) Schematic:

CIRCUIT DESCRIPTION
The Exhaust Gas Recirculation (EGR) valve vacuum is controlled by a Powertrain Control Module (PCM) controlled solenoid valve. The PCM will turn the EGR "ON" and "OFF" (duty cycle) by grounding CKT 435. The duty cycle is calculated by the PCM based on information from the engine coolant temperature, Manifold Absolute Pressure (MAP), vacuum, Throttle Position Sensor (TPS) and engine RPM. There should be no EGR when TP sensor input is below 3%, TP sensor indicating over 50% throttle, low vacuum or low engine coolant temperature.
With the ignition "ON" engine stopped, the EGR solenoid valve is de-energized and by grounding the diagnostic "test" terminal, the solenoid valve is energized.

DIAGNOSTIC TROUBLE CODE (DTC) CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. The remaining test checks the ability of the EGR valve to interact with the exhaust system. This system uses a negative backpressure EGR valve which should hold vacuum with engine "OFF."
2. When engine is started, exhaust backpressure at the base of the EGR valve should open the valve's internal bleed and vent the applied vacuum allowing the valve to seat.

DIAGNOSTIC AIDS
During normal EGR valve operation, the movement of the EGR valve pintle is small. It is important to determine whether or not the valve pintle moves and not how much it moves.
Suction from shop exhaust hoses can alter backpressure and may affect the functional check of the EGR valve.