18X REFERENCE SIGNAL CIRCUIT
Ignition Control Module (ICM) produces 18X reference signal.
ICM calculates 18X reference signal by filtering Crankshaft Position
(CKP) sensor 18X pulses when engine is running and CKP pulses are also
being received. PCM uses this information to calculate engine speed
and CKP at engine speeds less than 1200 RPM. PCM compares number of
18X reference pulses to 3X reference pulses and Camshaft Position
(CMP) pulses. If PCM receives incorrect number of pulses, DTC P0336
Engine may not start.
- Ratio of 18X reference pulses to 3X reference pulses received
by PCM does not equal 6.
- Ratio of 3X reference pulses to CMP pulses received by
PCM equals 6.
- Check for faulty connections at ICM.
- Check for broken/frayed wires leading to the ICM
- Start engine and check tachometer, if reading zero, check tach wire.
- Replace ICM.
- Check for incorrect harness routing near secondary
ignition components, ignition coil arcing to wiring harness or ICM.
Check ignition coils for cracks, carbon tracking or other signs of