DTC P0400: EGR Function: Description

This system cuts and controls vacuum applied to the EGR valve to suit engine operating conditions. This cut-and-control operation is accomplished through the ECM and the EGR Control (EGRC) solenoid valve. On 2.4L models, the solenoid valve is normally open. Vacuum is applied to the EGR valve. ECM applies ground to cause solenoid to vent vacuum. On 3.3L models, the solenoid valve is normally closed. Vacuum is vented. ECM applies ground to cause solenoid to apply vacuum to EGR valve. On all models, inputs to ECM for EGR valve control include the following:

• Camshaft Position Sensor (engine speed)
• Mass Air Flow Sensor (amount of intake air)
• Engine Coolant Sensor (engine coolant temperature)
• Intake Air Temperature Sensor (intake air temperature) 2.4L Only
• Ignition Switch (start signal)
• Throttle Position Sensor (throttle position)
• Vehicle Speed Sensor (vehicle speed) 2.4L Only

When the ECM detects any of the following conditions, the vacuum is discharged into the atmosphere. The EGR valve remains closed.

• Low engine coolant temperature.
• Engine starting.
• High-speed engine operation.
• Engine idling.
• Excessively high engine coolant temperature.
• Mass airflow sensor malfunction.
• Low intake air temperature.