Circuit Description

ECM will compare secondary current reading to predetermined maximum and minimum thresholds. If secondary current signal pulse is out of predetermined range, fail counter will be incremental. If failure counter exceeds calibration, test is complete and failure will be reported. If sample threshold is reached before failure threshold, test is complete and pass will be reported. ECM will detect an open or short circuit in secondary current sensing input circuit, misfire on entire bank for secondary current sense input circuit, coil failure and internal ION Sensing Module (ION) faults.

When DTC sets, ECM illuminates MIL as soon as fault was detected. ECM calculates an air flow value based on idle air control valve position, throttle position, RPM and barometric pressure. ECM will store conditions present when DTC was set as freeze frame data in the FAILURE RECORDS data.

ECM will turn MIL off on third consecutive trip cycle during which diagnostic runs and fault is no longer recognized. A history DTC will clear after 40 consecutive trip cycles during which diagnostic runs and fault is no longer recognized. DTC can be cleared with scan tool, or by disconnecting battery voltage feed to ECM.