gm cop bad spark line

donnyo · Post by **donnyo** » Fri Feb 07, 2020 4:51 pm

on this waveform why is my firing line going negative, this is on a gm truck coil with ballast circuit.

Technician · Post by **Technician** » Fri Feb 07, 2020 7:36 pm

Nothing to do with the truck, its the scope settings chosen. Select "Automotive" from the menu at the top of the screen and then select the ignition system type you want to test, using the type of equipment you have, and then depress the space bar and test the ignition. If you then compare your settings to the sample ones you should see where mistakes are being made.

donnyo · Post by **donnyo** » Sat Feb 08, 2020 3:04 pm

No I can get good waveforms with the settings I chose, what I found was the car was running non resistor spark plugs. Switched the plug to a resistor type and it cleaned the waveform up.

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