Oscilloscope Patterns and Waveforms

WAVE PATTERN INSPECTION USING AN ANALYZER

Ignition Coil And Power Transistor:

- Ignition coil primary signal
- Ignition power transistor control signal

Measurement method
1. Disconnect the ignition power transistor connector, and connect the special tool (test harness: MB991348) in between. (All terminals should be connected.)
2. Connect the analyzer special patterns pickup to ignition power transistor unit connector terminal No 6.

Alternate method (test harness not available)
1. Connect analyzer special patterns pickup to ECM terminal 10 for ignition power transistor.

Ignition Coil And Power Transistor:

Ignition Coil And Power Transistor Waveforms:

Standard Wave Pattern

Ignition Coil And Power Transistor Waveforms:

Wave Pattern Observation Points

Ignition Coil And Power Transistor Waveforms:

Examples Of Abnormal Wave Patterns

- Example 1
Wave pattern during engine cranking

Cause of problem
Open-circuit in ignition primary circuit

Wave pattern characteristics
Top-right part of the build-up section cannot be seen, and voltage value is approximately 2V too low.

- Example 2
Wave pattern during engine cranking

Cause of problem
Malfunction in ignition power transistor

Wave pattern characteristics
Power voltage results when the ignition power transistor is ON.