Oscilloscope Patterns and Waveforms

IGNITION COIL AND IGNITION 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 the ignition power transistor connector terminal 2 (No.2 - No. 3) and terminal 7 (No. 1 - No.4) respectively.

ALTERNATE METHOD (TEST HARNESS NOT AVAILABLE)
1. Connect the analyzer special patterns pickup to ECM terminal 10 and connection terminal 23 respectively.




STANDARD WAVE PATTERN




OBSERVATION CONDITIONS




WAVE PATTERN OBSERVATION POINTS
Point: Condition of wave pattern build-up section and maximum voltage







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.