The purpose of this test is to check the signal from an inductive Crankshaft Position (CKP) sensor, with no reference voltage, during engine cranking.
These known good waveforms have the following characteristics:
A CKP sensor provides an Engine Control Module (ECM) with its primary engine timing reference signal. The ECM uses it to calculate the engine speed and position for accurate injection and ignition control. The signal is also used to detect engine speed anomalies from misfires etc.
An inductive CKP sensor consists of a circuit with a wire coiled around a magnet. The sensor is accompanied by a pulse wheel, typically arranged about the flywheel circumference. The pulse wheel passes through and disturbs the sensor magnetic field inducing a circuit voltage. The induced voltage depends on engine speed: the faster the pulse wheel rotates, the greater the magnetic field disturbance.
When either the tooth or gap centres align with the sensor, there is an equal and opposite magnetic field disturbance and no voltage is induced. Conversely, as either a tooth leading or trailing edge aligns with the sensor, the magnetic field disturbance and induced voltage are greatest.
Positive voltage is produced when a tooth leading edge is closer than its trailing edge, and a negative voltage is produced in the opposite case.
The missing tooth on the pulse wheel provides the main timing reference mark. As the gap passes through the magnetic field, there is a period of reduced disturbance and voltage. Furthermore, the trailing and leading edge of the teeth that immediately precede and follow the gap are further apart, thus they produce a larger net magnetic field disturbance and induced voltage.
A two pin CKP sensor and ECM circuit can be arranged in two ways, with either:
The CKP sensor signal is critical to ECM operation and failures can cause symptoms such as:
Possible faults are:
Selection of component related Diagnostic Trouble Codes (DTCs)
P0016 Crankshaft Position - Camshaft Position Correlation Bank 1 Sensor A
P0017 Crankshaft Position - Camshaft Position Correlation Bank 1 Sensor B
P0018 Crankshaft Position - Camshaft Position Correlation Bank 2 Sensor A
P0019 Crankshaft Position - Camshaft Position Correlation Bank 2 Sensor B
P0315 Crankshaft Position - system variation values are not stored in the PCM memory
P0335 Crankshaft Position Sensor A Circuit Malfunction
P0336 Crankshaft Position Sensor A Circuit Range/Performance
P0337 Crankshaft Position Sensor A Circuit Low Input
P0338 Crankshaft Position Sensor A Circuit High Input
P0339 Crankshaft Position Sensor A Circuit Intermittent
P0385 Crankshaft Position Sensor B Circuit Malfunction
P0386 Crankshaft Position Sensor B Circuit Range/Performance
P0387 Crankshaft Position Sensor B Circuit Low Input
P0388 Crankshaft Position Sensor B Circuit High Input
P0389 Crankshaft Position Sensor B Circuit Intermittent
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