System Diagnosis - Exhaust Gas Recirculation (EGR) System

NBP EGR 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 control of the EGR is based on the following inputs:

^ Engine coolant temperature - above 25° C.

^ TP - "OFF" idle.

^ MAP.

DTC 32 will detect a faulty solenoid, vacuum supply, EGR valve or plugged passage. This chart checks for plugged EGR passages, a sticking EGR valve, or a stuck open or inoperative solenoid.

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

1. Checks for solenoid stuck open.

2. Checks for solenoid always being energized.

3. Grounding test terminal should energize solenoid and vacuum should drop.

4. Negative backpressure valve should hold vacuum with engine "OFF."

5. When engine is started, exhaust backpressure should cause vacuum to bleed off and valve to fully close.