Circuit Description
INSERT GRAPHIC SMITL15AA
The linear exhaust gas recirculation (EGR) system consists of a linear EGR valve, the powertrain control module (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, a diagnostic feedback signal can determine if the had actually moved. DTC P0405 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.
Conditions for Setting the DTC
DTC P0405 will set if the following conditions are met:
| • | The IGN voltage is above 11.0 volts. |
| • | The voltage is less than 0.20 volts or greater than 4.8 volts. |
| • | The condition is present for greater than 5 seconds. |
When this DTC fails, the EGR will be disabled for the entire ignition cycle. The malfunction history record will aid in diagnosis.
Diagnostic Aids
When attempting to diagnose an intermittent problem use the scan tool to review the 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. |
| • | Check the EGR 10 amp fuse in the 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. |
Test Description
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Normal closed valve position feedback voltage should be between 0.20-1.5 volts. This value may change with temperature.
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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.
