Ignition Control Module: Testing and Inspection

IGNITION COIL AND IGNITION POWER TRANSISTOR
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.

Standard Wave Pattern




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 too low, approximately 2 Volt.




- 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.

IGNITION COIL (WITH BUILT-IN IGNITION POWER TRANSISTOR) CHECK
Check by the following procedure, and replace if there is a malfunction.




SECONDARY COIL RESISTANCE CHECK
Measure the resistance between the high-voltage terminals of the ignition coil.

Standard value: 14 - 21 kOhms







PRIMARY COIL AND IGNITION POWER TRANSISTOR CONTINUITY CHECK

NOTE:
1. An analog-type ohmmeter should be used.
2. Connect the negative (-) probe of the ohmmeter to terminal 1.

CAUTION: This test must be performed quickly (in less than 10 seconds) to prevent coil from burning and ignition power transistor from breaking.