Circuit Description

The ECM uses pick-up coil input signals to switch primary ignition circuit on and off. Primary circuit is turned off when ECM delivers a signal to ignitor on the IGT wire, causing ignition coil to fire spark plug. After delivering a command to turn off primary circuit on IGT wire, the ECM monitors IGF circuit to ensure primary switching occurred. DTC is set when no IGF signal to ECM for 4-7 consecutive IGT signals during engine operation (3000 RPM or less). Possible causes are:

• IGF or IGT open or short circuit.
• Ignitor.
• ECM.