Cylinder Identification Sensor: Description and Operation

PURPOSE
In a Sequential Electronic Fuel Injection (SEFI) system each individual fuel injector is energized just prior to the opening of its corresponding intake valve. The Camshaft Position (CMP) sensor is used to identify when number 1 cylinder is on compression stroke and to generate the Cylinder Identification (CID) signal. This CID signal allows the Powertrain Control Module (PCM) to sequence the fuel injectors in the correct order.

CONSTRUCTION
The camshaft position sensor is an integral part of the Crank Shaft Position Sensor (CKP). It is an additional phototransistor within the CKP, located inside of the distributor. It cannot be replaced separately and must be serviced as part of the distributor.

OPERATION
A slotted disc is mounted to the distributor shaft. As the shaft rotates a slot cut into the disc (corresponding to number 1 cylinder compression stroke) allows light from a photodiode to strike a phototransistor. The camshaft position sensor then creates a signal which is sent to the PCM.

RELATED DIAGNOSTIC TROUBLE CODES

DTC 214 - Cylinder Identification (CID) circuit failure.

DTC 244 - CID failure occurred during a cylinder balance self-test.