Faulty Ignition Coil No. 4
Ignition Coil No. 4 harness is open or shorted
Ignition Coil No. 4 circuit poor electrical connection
Faulty Engine Control Module (ECM)
Engine Light ON (or Service Engine Soon Warning Light)
Direct Ignition System (DIS) is a 1-cylinder ignition system that ignites one cylinder with one ignition coil. Ignitor is integral to ignition coil. The Engine Control Module (ECM) determines ignition timing and outputs a ignition signal (IGT) for each cylinder. Based on the IGT signals, power transistors in the ignitor cut of current to primary coil in ignition coil, causing ignition coil to fire spark plug. After delivering a command to turn off primary circuit on the IGT wire, ECM monitors IGF circuit to ensure primary switching occurred.