Oscilloscope Check

INJECTOR

Required Special Tool:
MB991348: Test Harness Set

Measurement Method
1. Disconnect the injector connector, and connect the test harness special tool (MB991348) in between. (All terminals should be connected.)




2. Connect the oscilloscope probe to injector connector terminal No. 2.

Alternate method (Test harness not available)
1. Connect the oscilloscope probe to ECM terminal No. 1. (When checking the number 1 cylinder.)
2. Connect the oscilloscope probe to ECM terminal No. 14. (When checking the number 2 cylinder.)
3. Connect the oscilloscope probe to ECM terminal No. 2. (When checking the number 3 cylinder.)
4. Connect the oscilloscope probe to ECM terminal No. 15. (When checking 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.