BY-PASS CIRCUIT OPEN
The 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 the
second 3X reference pulse is recognized by the PCM, PCM applies 5
volts to by-pass circuit, commanding ICM to switch spark advance to
PCM control (IC mode). If PCM detects an open in the IC circuit, DTC
will set. Engine will start and may run in by-pass mode timing.
You likely won't notice any drivability problems.
- PCM detects an open in by-pass circuit.