Circuit Description

PCM checks validity of signals used in ION Sensing Module under various conditions. Deceleration Fuel Cut Off (DFCO) test is performed to evaluate if Combustion Quality (CQ) signal pulse width is less than predetermined value, value it is expected to be during DFCO conditions. If CQ signal pulse width is more than predetermined threshold, fail counter will be incremented. If failure counter exceeds calibration, test is complete and a failure is reported. Power Enrichment (PE) test is performed to determine if CQ signal pulse width is less than predetermined value. Value it is expected to be during PE conditions. If CQ signal pulse width is more than predetermined threshold, fail counter will be incremented. If failure counter exceeds calibration, test is complete and a failure is reported. Combustion Quality (CQ) test is performed to check if inappropriate CQ signal status were detected. If CQ pulses, multiple CQ pulses or CQ pulse width calculation errors were detected, failure counter will be incremented. If failure counter exceeds calibration, test is complete and a failure will be reported. Conditions for setting DTC:

• Ignition voltage is between 10 and 16 volts.
• MAP sensor signal is between 26 and 100 kPa.
• Engine speed is between 650 and 6500 RPM.
• No Crank DTCs set.
• No System Voltage DTCs set.