Circuit Description

PCM directly controls the ground for the linear EGR valve when certain conditions have been met. PCM contains a diode feedback circuit which dissipates energy when the valve is cycled off. When PCM grounds the valve, a diagnostic feedback signal can determine if valve had actually moved. This DTC 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 will set when there is a short or open in circuit, EGR valve being commanded closed and the feedback voltage is too high (closed valve test) or if the actual position feedback signal does not match the desired position being commanded (pintle position error test). Actual feedback voltage must be within .5 volt (10 percent) of desired position. The malfunction history record will indicate which one of these tests has failed, to aid in diagnosis. EGR position error is continuously checked when the EGR is commanded on. The EGR valve may operate at any engine coolant temperature regardless of loop mode.