Test Description

The following list gives a description for appropriate step numbers in diagnostic procedure.

1. 1  - The DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS, prompts technician to complete some basic checks and store "Freeze Frame" data on scan tool if applicable. This creates an electronic copy of data taken when fault occurred. Information is then stored in scan tool for later reference.
2. 3  - This step checks for an EGR valve that is leaking, stuck open, or turned on at idle. A normal engine operating temperature is specified as 176°F (80°C) or more.
3. 4  - This step checks operation of EGR valve. EGR duty cycle output control is disabled by PCM when any DTCs are stored and when engine temperature is less than 176°F (80°C).
4. 8  - This step checks for a physically stuck EGR valve or plugged EGR passages.
5. 9  - This step checks ignition positive voltage supply to EGR coils.
6. 10  - This step determines whether an electrical fault is cause of EGR valve staying open. An EGR Valve Control circuit that becomes shorted or open when EGR valve is open, can cause valve to remain open at all times.
7. 12  This step checks for an EGR Valve Control circuit that is shorted to ground. If circuit wiring is okay, a faulty PCM with an internally shorted circuit can cause EGR valve to be open.