Oscilloscope Check

IGNITION COIL AND IGNITION POWER TRANSISTOR INSPECTION USING AN ANALYZER

Ignition Power Transistor Control Signal Measurement Method

1. Disconnect the ignition coil 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 coil connector terminal 3.

Alternate method (Test harness not available)

1. Connect the analyzer special patterns pickup to ECM terminal 10 (No. 1 - No. 4), terminal 23 (No. 2 - No. 3) respectively.




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.)

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 too low, approximately 2 V.




- 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.