Ignition Control Module: Testing and Inspection

IGNITION COIL AND IGNITION POWER TRANSISTOR

Required Special Tool:
- MB991348: Test Harness Set

Measurement Method
1. Disconnect the connector, and connect test harness special tool (MB991348) in between. (All terminals should be connected.)




2. Connect the oscilloscope probe to each ignition power transistor connector terminal to analyze each cylinder:
- Terminal No. 1 for the number 3 and 6 cylinders
- Terminal No. 2 for the number 2 and 5 cylinders
- Terminal No. 3 for the number 1 and 4 cylinders

Alternate method (Test harness not available)
1. Connect the oscilloscope probe to PCM terminal No. 11. (When checking the number 1 and 4 cylinders.)
2. Connect the oscilloscope probe to PCM terminal No. 12. (When checking the number 3 and 6 cylinders.)




Standard Wave Pattern




3. Connect the oscilloscope probe to PCM terminal No. 13. (When checking the number 2 and 5 cylinders.)




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 approximately 2 volts 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.