Exhaust Gas Recirculation: Testing and Inspection

Chart C-7 EGR Flow Check:

Exhaust Gas Recirculation Wiring Diagram:

Circuit Description:
The digital EGR valve is designed to accurately supply EGR to an engine independent of intake manifold vacuum. The valve controls EGR flow from the exhaust to the intake manifold through three orifices which increment in size to produce seven combinations. When a solenoid is energized, the armature with attached shaft and swivel pintle is lifted, opening the orifice.

The flow accuracy is dependent on metering orifice size only, which results in improved control.

Test Description:
Numbers below refer to circled numbers on the diagnostic chart.

1. DTC's should be diagnosed using appropriate charts before preparing a functional check.

2. This step activates each solenoid individually. As you energize #1 or #2 solenoid, the engine RPM should drop. #3 solenoid has the largest port and may stall the engine when energized.

Diagnostic Aids:
If the digital EGR valve shows signs of excessive heat (a melted condition), check the exhaust system for blockage (possibly a plugged converter). If the exhaust system is restricted, repair the cause. One possibility is an injector which is open due to one of the following:
^ Stuck
^ Grounded driver circuit
^ Possibly defective ECM

If this condition is found, the oil should be checked for possible fuel contamination.