Part 2 of 2

Chart C-7 Part 2 Of 2:

Chart C-7 Wiring Diagram:

Circuit Description:

The Exhaust Gas Recirculation (EGR) valve is controlled by a normally closed solenoid valve. The ECM turns the solenoid valve "ON" to allow vacuum to pass to the EGR, and turns the solenoid valve "OFF" to prevent EGR operation.

The duty cycle is calculated by the ECM based on information from the ECT, IAT, TP sensor, and MAP sensors. Also, engine RPM and the PNP switch input affect EGR. There should be no EGR when in park or neutral, TP sensor below a calibrated value, or TP sensor indicating WOT.

With the ignition "ON" and engine "OFF," the EGR solenoid valve is de-energized. The solenoid valve, however, should be energized, if the diagnostic "test" terminal is grounded with the ignition "ON" and engine "OFF."



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:

Suction from shop exhaust hoses can alter backpressure and may affect the functional check of the EGR valve.

During normal EGR valve operation, the movement of the EGR pintle is small. It is important to determine whether the valve pintle moves and not how much it moves.