Theory Of Operation

WARNING: This page is about a different variant/trim than selected.

The Camshaft Position (CMP) Sensor circuits consist of an Powertrain Control Module (PCM) supplied 5-volt reference circuit, low reference circuit, and an output signal circuit. The CMP Sensor is an internally magnetic biased digital output integrated circuit sensing device. The sensor detects magnetic flux changes between the peaks and valleys of a tone wheel attached to the camshaft. As each tooth rotates past the CMP Sensor, the resulting change in the magnetic field is used by the sensor electronics to produce a digital output pulse. The sensor returns a digital ON/OFF DC voltage pulse of varying frequency output pulses per Camshaft revolution that represent an image of the camshaft tone wheel. The frequency of the CMP Sensor output depends on the velocity of the camshaft. The PCM decodes the tooth pattern to identify camshaft position. This information is then used to sequence the ignition timing and fuel injection events for the engine. The PCM also uses CMP Sensor output information to determine the camshaft relative position to the Crankshaft, to control the CMP Actuator operation if equipped.

NOTE:

The engine may still start even if either the CKP or CMP fails. The PCM eventually sorts out engine position and starts the vehicle on just one of these two inputs. However, there is a slight delay in starting until the PCM can establish sync. A DTC is set and the MIL illuminates if either of the CKP or CMP Sensor signals are not present during engine cranking.

The table below calls out the names of the timing components and which Camshaft they are associated with. This information is intended to aid in diagnosing the proper component when performing DTC diagnostics.

2.0L/2.4L World Engine and 2.0L GMET 4 VVT Engine Component Locations
CAMSHAFT	CAMSHAFT SOLENOID LOCATIONS	CAM PHASER/OIL CONTROL VALVE LOCATIONS	CAM SENSOR LOCATIONS
INTAKE CAM	Bank 1 Position 1 (Camshaft Position Solenoid 1/1)	Camshaft 1/1 Phaser and Oil Control Valve	CMP Sensor Bank 1 Sensor 2 (CMP Sensor 1/2)
EXHAUST CAM	Bank 1 Position 2 (Camshaft Position Solenoid 1/2)	Camshaft 1/2 Phaser and Oil Control Valve	CMP Sensor Bank 1 Sensor 1 (CMP Sensor 1/1)