Oscilloscope Check

IGNITION COIL AND IGNITION POWER TRANSISTOR INSPECTION PROCEDURE USING AN ANALYZER

Measurement Method
1. Disconnect the distributor (ignition power transistor) connector and connect the special tool (test harness: MB991348) in between. (All terminals should be connected.)




2. Connect the analyzer special patterns pickup to distributor connector terminal 3.

Alternate method (Test harness not available)
1. Connect the analyzer special patterns pickup to ECM terminal 10.




Observation conditions

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 V.




- 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