Oscilloscope Patterns and Waveforms

IGNITION COIL AND POWER TRANSISTOR MEASUREMENT METHOD
1. Disconnect the distributor (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 distributor connector terminal 6.

ALTERNATE METHOD (Test Harness Not Available)
1. Connect the analyzer special patterns pickup to ECM terminal 10.




OBSERVATION CONDITIONS







STANDARD WAVE PATTERN
Wave Pattern Observation Points:
Point: Condition of wave pattern build-up section and maximum voltage
(Refer to abnormal wave pattern examples 1 and 2.)




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 in ignition power transistor

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