Ignition Control Module: Testing and Inspection
IGNITION COIL AND IGNITION POWER TRANSISTORRequired 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.)
Observation Conditions:
2. Connect the oscilloscope probe to distributor connector terminal 3.
Alternate method Crest harness not available)
1. Connect the oscilloscope probe to PCM terminal 11.
Standard Wave Pattern
Observation Conditions:
Observation conditions
Standard Wave Pattern:
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 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."