Ignition Relay: Testing and Inspection

Ignition Coil And Power Transistor:

Wave Pattern Inspection Using an Analyzer
- Ignition coil primary signal

Refer to GROUP 8-Ignition System

- Ignition power transistor control signal

Measurement method

1. Disconnect the 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 ignition power transistor unit connector terminal �.

Alternate method (test harness not available)

1. Connect analyzer special patterns pickup to ECM terminals 10 for ignition power transistor.
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 2V 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.
INSPECTION Using Scan Tool