Oscilloscope Patterns and Waveforms

Wave Pattern Inspection Using an Analyzer
- Ignition coil primary signal
- Ignition power transistor control signal

Measurement method
(1) Disconnect the connector of the power transistor, and connect the special tool (test harness: MB991348) across the disconnected connector parts.
(2) Sequentially connect the special patterns pickup of the analyzer to each of terminal (1) (No.3 - No.6), terminal (2) (No.2 - No.5) and terminal (3) (No.1 - No.4) of the ignition power transistor unit connector.

Alternative method (when test harness is not available)
Connect the analyzer special patterns pickup to ECM terminals (10), (11) and (23) for the ignition power transistor.




Standard Wave pattern Observation Condition




Standard Wave pattern




Wave pattern observation points
Point: Condition of wave pattern build-up and maximum voltage (Refer to abnormal wave pattern examples 1 and 2.)




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 2 V too low.




- Example 2
Wave pattern during engine cranking
Cause of problem
Malfunction of ignition power transistor
Wave pattern characteristics
Power voltage results when the ignition power transistor is on.