Oscilloscope Patterns and Waveforms
INSPECTION PROCEDURE USING AN OSCILLOSCOPERequired Special Tools:
MB991348: Test Harness
MD998464: Test Harness
Measurement Method
1. Disconnect the injector Intermediate connector, and connect the test harness special tool (MD998464) in between.
2. Connect the oscilloscope probe to injector connector terminal 2.
Alternate method (Test harness not available)
1. Connect the oscilloscope probe to PCM terminal 1. (When checking the number 1 cylinder.)
2. Connect the oscilloscope probe to PCM terminal 9. (When checking the number 2 cylinder.)
3. Connect the oscilloscope probe to PCM terminal 24. (When checking the number 3 cylinder.)
4. Connect the oscilloscope probe to PCM terminal 2. (When checking the number 4 cylinder.)
Standard Wave Pattern:
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.