MPI <4G63>
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Troubleshooting
13D-89
Wave Pattern Observation Points
Point: Condition of wave pattern build-up section and maximum voltage (Refer to abnormal wave pattern
examples 1 and 2).
Condition of wave pattern build-up section and maximum voltage
Probable cause
Rises from approximately 2 V to approximately 4.5 V at the
top-right
Normal
2 V rectangular wave
Open-circuit in ignition primary circuit
Rectangular wave at power voltage
Power transistor malfunction
Examples of Abnormal Wave Patterns
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Example 1
Wave pattern during engine cranking
Cause of problem
Open-circuit in ignition primary circuit
Wave pattern characteristics
Top
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right part of the build
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up section cannot be seen,
and voltage value is approximately 2 V too low.
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Example 2
Wave pattern during engine cranking
Cause of problem
Malfunction in power transistor
Wave pattern characteristics
Power voltage results when the power transistor is ON.
Normal wave pattern
2 V
V
B
Normal wave pattern