Ignition Control Module: Testing and Inspection

IGNITION COIL AND IGNITION POWER TRANSISTOR

Required Special Tool:
- MB991658: Test Harness

Measurement Method




1. Disconnect the ignition coil connector and connect test harness special tool (MB991658) between the separated connector. (All terminals should be connected.)
2. Connect the oscilloscope probe to ignition coil connector terminal No.3.

Alternate method (Test harness not available)
1. Connect the oscilloscope probe to ECM or PCM terminal No.31. (When checking the number 1 cylinder.)
2. Connect the oscilloscope probe to ECM or PCM terminal No.32. (When checking the number 2 cylinder.)
3. Connect the oscilloscope probe to ECM or PCM terminal No.35. (When checking the number 3 cylinder.)
4. Connect the oscilloscope probe to ECM or PCM terminal No.52. (When checking the number 4 cylinder.)

Standard Wave Pattern

Wave Pattern Observation Points

Point: The power transistor control signal (ignition timing) is advanced when the engine speed is increased.

Examples of Abnormal Wave Patterns

Example 1 (Wave pattern during engine cranking)

- Cause of problem
Open-circuit in ignition primary circuit

- Wave pattern characteristics
Voltage value is too low.