Camshaft Position Sensor

CAMSHAFT POSITION SENSOR





OPERATION
The camshaft position sensor functions to detect the top dead center position of the No. 1 cylinder and to convert those data to pulse signals that are input to the engine control module. The engine control module, based upon those signals, calculates the sequence of fuel injection.

The power for the camshaft position sensor is supplied from the MFI relay and is grounded to the vehicle body. The camshaft position sensor, by intermitting the flow (to ground) of the 5 V voltage applied from the engine control module, produces pulse signals.

TROUBLESHOOTING HINTS
If there is a malfunction for the camshaft position sensor, the sequential injection will not be correct, resulting in such problems as engine stalling, unstable idling, and poor acceleration.

INSPECTION

Wave Pattern Inspection Using an Analyzer





Measurement Method
(1) Disconnect the distributor connector and connect the special tool (test harness: MB991 348) in between. (All terminals should be connected.)
(2) Connect the analyzer special patterns pickup to terminal (1) of the distributor connector. (When inspecting the camshaft position sensor signal wave pattern.)
(3) Connect the analyzer special patterns pickup to terminal (2) of the distributor connector. (When inspecting the crankshaft position sensor signal wave pattern.)

Alternative method (when test harness is not available)
(1) Connect the analyzer special patterns pickup to ECM terminal (68) for the camshaft position sensor.
(2) Connect the analyzer special patterns pickup to ECM terminal (69) for the crankshaft position sensor.






Wave pattern observation points
- Check that cycle time T becomes shorter and the frequency increases when the engine speed is increased.


Examples of abnormal wave patterns

- Example 1




Cause of problem
- Malfunction of sensor interface

Wave pattern characteristics
- Short wave pattern is output even when the engine is not started.


- Example 2




Cause of problem
- Loose timing belt
- Abnormality in sensor disk

Wave pattern characteristics
- Wave pattern is displaced to the left or right.


HARNESS INSPECTION