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.)

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."