GM Bypass Ignition System Operation (part 1)

Part 2 https://youtu.be/vmutNjx7QDY
This is a unique design when it comes to ignition systems. One where the ignition module can control spark completely independent from the engine computer and is something GM used for many years. Starting with their computer controlled distributor ignition systems in the early 80s and continuing in many different waste spark designs well into the late 90s.
The engine being discussed is an older GM 3300 but the material can be applied to all GM bypass ignition systems.

This lecture was given to my class in connection with the following case study:
- GM 3300 Intermittent no start rough idle (shorted injectors)
https://youtu.be/vmutNjx7QDY

Related videos
- How to test a GM ignition module (crank sensor bypass test) - VRS https://youtu.be/fra26yyyc-I
- ScannerDanner gets his butt kicked by an '88 F-150 (EEC-IV Ignition) https://youtu.be/6UPe5f1s2ak

Topics discussed
- How a bad ignition module can cause a no injector pulse condition with good spark.
- How electronic spark timing works
- What is the difference between "Module mode" and "EST mode"
- what the "reference "wire is used for and why you want to remember the wire color
- how to perform a bypass test on the reference circuit to check for injector pulse
Playlist
- (Chapter 22) No Spark Troubleshooting, Ignition Coil & Module Testing https://www.youtube.com/playlist?list=PLAFYVCyenqcpihCBcez4sWLv5x2FHNnq-

For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available at www.scannerdanner.com as an eBook or paper book.
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Видео GM Bypass Ignition System Operation (part 1) канала ScannerDanner