58X Reference ECM Input

The engine control module (ECM) uses this signal from the crankshaft position (CKP) sensor to calculate engine RPM and crankshaft position at all engine speeds. The ECM also uses the pulses on this circuit to initiate injector pulses. If the ECM receives no pulses on this circuit, DTC P0337 will set. The engine will not start and run without using the 58X reference signal.