Camshaft Position Sensor: Testing and Inspection

CAMSHAFT POSITION SENSOR



OPERATION
- The camshaft position sensor senses the top dead center on compression stroke, converts it into a pulse signal and inputs it to the engine control module, which then computes the fuel injection sequence, etc. based on the input signal.
- Power to the camshaft position sensor is supplied from the multiport fuel injection relay and is grounded to the body. The camshaft position sensor generates a pulse signal as it repeatedly connects to and disconnects from the 5 V voltage supplied from the engine control module and ground.

TROUBLESHOOTING HINTS
Hint 1:
If the camshaft position sensor does not function correctly, correct sequential injection is not being carried out, so that the engine may stall, run irregularly at idle or fail to accelerate normally.
Hint 2:
If the sensor outputs a pulse signal when the ignition switch is turned ON (without starting the engine), the cause is probably a malfunction of the camshaft position sensor or engine control module.




INSPECTION

Wave Pattern Inspection using an Analyzer Measurement method
1. Disconnect the connector of the camshaft position sensor, and connect the special tool (test harness: MB991348) across the disconnected connector parts. (Connect the tool to all terminals.)
2. Connect the special patterns pickup of the analyzer to the terminal (2) of the camshaft position sensor connector.
3. Disconnect the connector of the crankshaft position sensor, and connect the special tool (test harness: MD998478) across the disconnected connector parts.
4. Connect the special patterns pickup of the analyzer to the terminal (2) of the crankshaft position sensor connector.








Alternative Method (when Test Harness Is Not Available)
1. Connect the analyzer special patterns pickup to ECM terminal (88) for the camshaft position sensor.
2. Connect the analyzer special patterns pickup to ECM terminal (89) for the crankshaft position sensor.

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





STEP 1. Check for continuity between the camshaft position sensor and the MFI relay.
- MFI relay connector: Disconnected
- Camshaft position sensor connector: Disconnected

NOTE:
- Insert the probes of the circuit tester into both ends of the harness.

OK: GO TO STEP 2
NG: Repair the harness. (A3 - B3)





STEP 2. Check for continuity in the ground circuit.
- Camshaft position sensor connector: Disconnected

OK: GO TO STEP 3
NG: Repair the harness. (A1 - Ground)





STEP 3. Check for an open circuit or a short-circuit to ground between the camshaft position sensor and engine control module.
- Engine control module connector: Disconnected
- Camshaft position sensor connector: Disconnected

OK: GO TO STEP 4
NG: Repair the harness. (A2 - 88)





STEP 4. Measure the applied voltage.
- Camshaft position sensor connector: Disconnected
- Engine control module connector: Connected
- Ignition switch: ON

Voltage (V): 4.8 - 5.2

OK: STOP
NG: Replace the engine control module.