Component Tests and General Diagnostics

Chart C-7 - EGR System Check:

Wiring Diagram For Chart C-7 - EGR Check:

CHART C-7 - EXHAUST GAS RECIRCULATION SYSTEM CHECK


Circuit Description:

The Exhaust Gas Recirculation (EGR) valve is controlled by a normally closed solenoid (allows vacuum to pass when energized). The ECM energizes the solenoid to turn the EGR on, and monitors EGR flow with the EGR temperature switch. Code 32 will detect a faulty solenoid, temperature switch, or vacuum supply. Chart C-7 checks for plugged EGR passages, a sticking EGR valve, or a stuck open solenoid.

The ECM controls EGR based on the following inputs:

^ Engine Coolant - about 25~C
^ Throttle Position Sensor - off idle and steady
^ Manifold Absolute Pressure - steady throttle


Test Description:

1. With the ignition "ON", engine stopped, the solenoid should not be energized and vacuum should not pass to the EGR valve.

2. Grounding the diagnostic terminal will energize the solenoid and allow vacuum to pass to valve.


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