P0404

Diagnostic Chart:

Wiring Diagram:

The linear EGR system consists of a linear EGR valve, the PCM and its associated wiring. The EGR valve solenoid is controlled directly by the PCM when certain conditions have been met. The PCM contains a diode feedback circuit which dissipates energy when the valve is cycled Off. When the PCM grounds the valve, the diagnostic feedback signal can determine if the valve had actually moved. DTC P0404 has been defined to monitor the feedback signal. This diagnostic will determine if the position feedback signal properly falls within the correct range under different valve operating conditions.

DTC PARAMETERS

^ If commanded position is greater than 80%, actual position must be within 26 counts (10% [0.5 volts]) of commanded.

^ If commanded position is less than 80%, actual position must be within 60 counts (24% [1.1 volts]) of commanded.


DTC P0404 will set if either condition exists for greater than 10 seconds.

When either one of these tests have failed, a DTC will set and EGR will be disabled for that ignition cycle. The malfunction history record will indicate which one of these tests has failed to aid in diagnostics.

IMPORTANT: The EGR position error is continuously checked when the EGR is commanded On.

IMPORTANT: The EGR valve may operate at any engine coolant temperature regardless of loop mode.

TEST DESCRIPTION

1. Normal closed valve position feedback voltage should be between 0.20-1.5 volts. This value may change with temperature.

2. A voltage of less than 0.2 volts indicates a problem with the position feedback circuit. A voltage of greater than 1.5 volts could be caused by a position feedback circuit problem, a valve stuck open or a solenoid being energized.

DIAGNOSTIC AIDS

When attempting to diagnose an intermittent problem, use the Scan tool to review malfunction history diagnostic information. The supplemental data can be used to duplicate a problem.

Check the tightness of the female terminal grip with a spare male terminal.

^ B+ voltage is supplied to the E terminal on the EGR valve when the ignition is On.

^ heck EGR 10-amp fuse in the Under Hood Junction Block (UHJB) before diagnosing this DTC.

^ Carbon buildup around the pintle valve may restrict pintle movement.

^ An open in the diode feedback circuit will result in unstable valve operation resulting in vehicle surge.