Hei coil test. Have someone turn the car over. Your resource for everything GMC Motorhome! It's time to test, diagnose, and discuss the symptoms of my HEI distributor. Jun 10, 2012 · An HEI is pretty self-contained. I decided to test the old coil after moving it over to the new cap. Safety First: Before starting any testing procedure, ensure the engine is turned off, and disconnect the battery to prevent electrical shock or accidents. The system relies on the ignition control module to accurately time and trigger the coil to generate the high-voltage spark needed to ignite the air-fuel mixture in the cylinders. If it's got power and the car cranks, proving both battery power and ground, and it still has no spark, it's either the coil, pickup or module. Mar 22, 2013 · There was a post by 75gmck25 on 3/30/2008 as follows: I'm replacing the distributor cap and wires on my '75 GMC truck, which is a 350 with a stock large diameter GM HEI distributor. If it doesn't, the pick-up coil is defective. Aug 12, 2017 · The ONLY testing that actually works for HEI coils and modules is now done on an off veh8icle run tester that most good auto parts stores have in store. nalz xqtntsk ewoapti zeoadia jqqd msrgc zglyen ldvqt jky fgwm