Circuit Description

Ignition signal and fail-safe signal provide crucial information in the control of ignition system timing, injector timing and fail-safe activation. Based on initial timing calculated by crankshaft and camshaft sensor signals, PCM sends an ignition signal to ignitor and uses it as a reference point to determine ignition dwell.

A circuit within ignitor controls ignition dwell and spark period by controlling power transistor switch on and off. After spark has occurred, ignitor sends an ignition fail-safe signal to PCM, confirming an ignition event has taken place. If fail-safe signal is not received by PCM, fail-safe mode is activated and fuel injector operation is ceased to prevent catalytic converter damage. DTC P1300 will set when no ignition fail-safe signal is received by PCM for 4 consecutive ignition cycles.