1999 Chevrolet Express 2500, Ignition - Primary Waveform

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Posted to the Waveform Library on 2/19/2007

Ch1 (yel) is the #1 cylinder secondary Ch2 (green) EST from PCM to ICM Ch3 (blue) is CMP Ch4 (red) is ignition coil amperage

Note that the coil amperage is double firing the #1 cylinder as commanded by the PCM over the EST line. This PCM is no good. It is no...

Vehicle Data

1999 Chevrolet Express 2500 5.7L

Engine	5.7 L / 8 cyl / GAS
Trans	4-speed AutomaticTransmission (Electronic)
Delivery	Fuel Injection
Subsystem	ECM/Inputs/Outputs
Component	Ignition - Primary
Condition	Known Bad

References

TECH: 99 Tahoe heavy misfires, pinging, rattling

Vehicle Data

1999 Chevrolet Express 2500 5.7L

Engine	5.7 L / 8 cyl / GAS
Trans	4-speed AutomaticTransmission (Electronic)
Delivery	Fuel Injection
Subsystem	ECM/Inputs/Outputs
Component	Ignition - Primary
Condition	Known Bad

References

TECH: 99 Tahoe heavy misfires, pinging, rattling