Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSMITSUBISHI2004GALANT V6-3.8L (6G75)REPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSCRANKSHAFT POSITION SENSORTESTING AND INSPECTIONOSCILLOSCOPE CHECK
2004 Mitsubishi Galant V6-3.8L (6G75)
Oscilloscope Check
2004 Mitsubishi Galant V6-3.8L (6G75)SECTION Oscilloscope Check
INSPECTION PROCEDURE USING AN OSCILLOSCOPE
CRANKSHAFT POSITION SENSOR
Required Special Tools:
- MB991709: Test Harness
- MD998478: Test Harness
- MB991923: Power Plant ECU Check Harness
Measurement Method
1. Disconnect the 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 camshaft position sensor connector terminal No. 2.
3. Disconnect the crankshaft position sensor connector, and connect the test harness special tool (MD998478) between the separated connector.
4. Connect the oscilloscope probe to crankshaft position sensor connector terminal No. 2 (black clip of special tool).
Alternate method (Measure at the PCM)
1. Disconnect the all PCM connectors, and connect check harness special tool (MB991923) between the separated connectors.
2. Connect the oscilloscope to check harness terminal No. 104 (Check the camshaft position sensor signal wave pattern).
3. Connect the oscilloscope to check harness terminal No. 103 (Check the crankshaft position sensor signal wave pattern).
Standard Wave Pattern
Wave Pattern Observation Points
1. Check that cycle time becomes shorter when the engine speed increased
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 belt.
- Abnormality in sensor disc.
Wave pattern characteristics
- Wave pattern is displaced to the left or right
CRANKSHAFT POSITION SENSOR
Required Special Tools:
- MB991709: Test Harness
- MD998478: Test Harness
- MB991923: Power Plant ECU Check Harness
Measurement Method
1. Disconnect the 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 camshaft position sensor connector terminal No. 2.
3. Disconnect the crankshaft position sensor connector, and connect the test harness special tool (MD998478) between the separated connector.
4. Connect the oscilloscope probe to crankshaft position sensor connector terminal No. 2 (black clip of special tool).
Alternate method (Measure at the PCM)
1. Disconnect the all PCM connectors, and connect check harness special tool (MB991923) between the separated connectors.
2. Connect the oscilloscope to check harness terminal No. 104 (Check the camshaft position sensor signal wave pattern).
3. Connect the oscilloscope to check harness terminal No. 103 (Check the crankshaft position sensor signal wave pattern).
Standard Wave Pattern
Wave Pattern Observation Points
1. Check that cycle time becomes shorter when the engine speed increased
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 belt.
- Abnormality in sensor disc.
Wave pattern characteristics
- Wave pattern is displaced to the left or right
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.