Oscilloscope Patterns and Waveforms

INSPECTION PROCEDURE USING AN OSCILLOSCOPE

INJECTOR

Required Special Tools:
- MB991658: Test Harness
- MB992110: Power Plant ECU Check Harness

Measurement Method.
1. Disconnect the injector connector, and connect the test harness special tool (MB991658) between the separated connector. (All terminals should be connected.)
2. Connect the oscilloscope probe to injector connector terminal No. 2.

Alternate method

1. Disconnect all ECM connectors. Connect the check harness special tool (MB992110) between the separated connectors.

2. Connect the oscilloscope probe to each check harness connector terminal to analyze each cylinder:
- Terminal No. 2 for the number 1 cylinder.
- Terminal No. 3 for the number 2 cylinder.
- Terminal No. 18 for the number 3 cylinder.
- Terminal No. 19 for the number 4 cylinder.

Standard Wave Pattern:

Wave Pattern Observation Points

Point A: Height of injector coil induced voltage.

Point B: Injector drive time

1. The injector drive time should be synchronized with the scan tool tester display.
2. When the engine is suddenly revved, the drive time will be greatly extended at first, but the drive time will soon return to original length.