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 is 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.

If commanded EGR position is greater than 80 percent, actual position must be within 26 counts (10 percent or .5 volt) of commanded position. If commanded position is less than 80 percent, actual position must be within 60 counts (24 percent or 1.1 volts) of commanded position. DTC 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 this ignition cycle. 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.