Oscilloscope Patterns and Waveforms

INSPECTION PROCEDURE USING AN OSCILLOSCOPE

INTAKE CAMSHAFT POSITION SENSOR AND CRANKSHAFT POSITION SENSOR










Required Special Tools:
- MB991709: Test Harness
- MB992110: Power Plant ECU Check Harness

Measurement Method

1. Disconnect the intake camshaft position sensor connector, and connect the test harness special tool (MB991709) between the separated connector (All terminals should be connected).
2. Connect the oscilloscope probe to intake camshaft position sensor connector terminal No. 3.
3. Disconnect the crankshaft position sensor connector, and connect the test harness special tool (MB991709) between the separated connector (All terminals should be connected).
4. Connect the oscilloscope probe to crankshaft position sensor connector terminal No. 3.

Alternate method







1. Disconnect all ECM connectors. Connect the check harness special tool (MB992110) between the separated connectors.







2. Connect the oscilloscope to check harness terminal No. 14. (Check the intake camshaft position sensor signal wave pattern.)
3. Connect the oscilloscope to check harness terminal No. 8. (Check the crankshaft position sensor signal wave pattern.)










Wave Pattern Observation Points
- Verify that the sensor signal frequency increases as the engine speed rises.

Examples of Abnormal Wave Patterns







Example 1
Cause of problem
- Sensor interface malfunction.

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







Example 2
Cause of problem
- Loose timing chain.
- Abnormality in sensor disc.

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

EXHAUST CAMSHAFT POSITION SENSOR AND CRANKSHAFT POSITION SENSOR










Required Special Tools:
- MB991709: Test Harness
- MB992110: Power Plant ECU Check Harness

Measurement Method

1. Disconnect the exhaust camshaft position sensor connector, and connect the test harness special tool (MB991709) between the separated connector (All terminals should be connected).
2. Connect the oscilloscope probe to exhaust camshaft position sensor connector terminal No. 3.
3. Disconnect the crankshaft position sensor connector, and connect the test harness special tool (MB991709) between the separated connector (All terminals should be connected).
4. Connect the oscilloscope probe to crankshaft position sensor connector terminal No. 3.

Alternate method







1. Disconnect all ECM connectors. Connect the check harness special tool (MB992110) between the separated connectors.







2. Connect the oscilloscope to check harness terminal No. 7. (Check the exhaust camshaft position sensor signal wave pattern.)
3. Connect the oscilloscope to check harness terminal No. 8. (Check the crankshaft position sensor signal wave pattern.)










Wave Pattern Observation Points
- Verify that the relative position of the exhaust camshaft position sensor's output wave changes when the low load operation changes to the high load operation.

Examples of Abnormal Wave Patterns







Example 1
Cause of problem
- Sensor interface malfunction.

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







Example 2
Cause of problem
- Loose timing chain.
- Abnormality in sensor disc.

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