Circuit Description

The ECM determines ignition timing and outputs a ignition signal (IGT1) to the ignitor. Primary circuit is turned off when ECM delivers a signal to ignitor on the IGT1 wire, causing ignition coil to fire spark plug. After delivering a command to turn off primary circuit on IGT1 wire, the ECM monitors IGF circuit to ensure primary switching occurred. DTC is set when there is no IGF signal to ECM for 4 consecutive IGT1 signals during engine operation. Possible causes are:

• IGF or IGT1 open or short circuit from ignitor to ECM.
• Ignitor.
• ECM.