Circuit Description

Ignition Control Module (ICM) sends signals that PCM requires for fuel control and spark advance calculations. At start of engine crank, ICM controls spark advance (by-pass mode). When second 3X signal is recognized by PCM, it applies 5 volts to bypass circuit, commanding ICM to switch Ignition Control (IC) of spark advance to PCM (IC mode). An open in IC circuit, or a short to voltage in bypass circuit will set DTC 1350.