DTC P1372: Crankshaft Position Sensor Circuits Performance: Description

The Powertrain Control Module (PCM) uses dual Crankshaft Position (CKP) "A" and CKP "B" sensors in order to determine the crankshaft position. The PCM supplies an ignition voltage and a ground for each sensor. During engine rotation, a slotted ring, machined into the crankshaft, causes the sensors to return a series of on and off pulses to the PCM. The PCM uses these pulses to decode the position of the engine crankshaft.

The PCM uses 2 basic methods of decoding the engine position, angle based and time based, using either CKP "A" or CKP "B" sensor input. During normal operation, the PCM uses the angle based method. In order to operate in this mode, the PCM must receive signal pulses from both CKP sensors. The PCM uses the signal pulses to determine an initial crankshaft position, and to generate medium resolution (24X reference) and low resolution (4X reference) signals. Once the initial crank position is determined, the PCM continuously monitors both sensors for valid signal inputs. As long as both signal inputs remain, the PCM will continue to use the angle based mode.

When either CKP signal is lost, the PCM will compare the medium resolution signal to the Camshaft Position (CMP) sensor signal. If the PCM detects a valid CMP signal, and the medium resolution to CMP signal correlation is correct, the PCM determines that CKP sensor "A" is at fault. However, if the medium resolution to CMP correlation is incorrect, the PCM determines that CKP sensor "B" is at fault. If, while in the angle based mode, the PCM detects an intermittent loss of either CKP signal, DTC P1372 will set.