Circuit Description

3X reference circuit is produced by Ignition Control Module (ICM). PCM uses 3X reference signal pulses to calculate engine speed (RPM) and crankshaft position at engine speed more than 1200 RPM. PCM uses pulses on this circuit to initiate injector pulses. If PCM receives incorrect number of pulses on 3X reference circuit, DTC P1374 will set.

Conditions required to set DTC are:

• Engine running and PCM is receiving 18X reference signal pulses.
• Ratio of 18X reference signal pulses to 3X reference signal pulses received by PCM do not equal 6.
• Ratio of 18X reference signal pulses to camshaft reference signal pulses received by PCM equals 36.
• Conditions present for up to 30 seconds or 100 crankshaft revolutions.