Circuit Description

ECM determines ignition timing and outputs a ignition signal to ignitor. Primary circuit is turned off when ECM delivers a signal to ignitor on IGT wire, causing ignition coil to fire spark plug. After delivering a command to turn off primary circuit, ECM monitors IGF circuit to ensure primary switching occurred. DTC is set when there is no IGF signal to ECM for 4 consecutive IGT signals during engine operation. Possible causes are:

• IGF or IGT circuit from ignitor to ECM is open or shorted.
• Defective ignitor.
• Defective ECM.