The General Motors HEI distributor first showed up in production vehicles in 1975. It's a one wire ignition system that has been used in a huge number of GM vehicles over many years. Although very dependable, there are some critical components that can fail. The pickup coil is one of those components. This video will show how to diagnose the pickup coil using three technics. We will use an ohm meter to check for coil resistance, an AC voltmeter to check for AC voltage output and a hand held oscilloscope to view the actual AC sine wave that the pickup coil will create. With the millions of HEI distributors that are used in vehicles that on the road today, this should be useful information.