guys.... i'm at my whits end. Just finishing up building a 66 chevy c10 short bed with 454 dual quad, th400 and this is the stanggest thing i have run into. I'm runnin a zz20 wiring harness and i've got everything working except when the engine is shut off the starter momentarily kicks. I mean it is like you just clicked the ignition. I searched the web and asked a bunch of people and haven't found an answer anywhere. Anyone got anything, it sure would help.
Sounds like you might have a voltage spike or "transient". Transients can occur when you turn OFF electro-mechanical devices such as motors and solenoids. Energy stored in magnetic fields of these devices can create voltage spikes of hundreds of volts when the power is suddenly removed as the magnetic energy is instantly converted back to electrical energy by the collapsing magnetic field. These spikes occur when the motor or solenoid is turned OFF not ON. These short lived voltage spikes usually do no damage to electrical devices but can destroy electronics or cause them to do things you don't expect or want. I don't know if it's possible to have enough energy to activate your starter solenoid or not but its something to think about.Possible source might electric cooling fan,fuel pump of AC clutch.
Disconnect the solenoid positive wire. Put a test light on it and have somebody turn the ignition on, to start, and back off. Sounds like you may see a flash of 12v when the ignition is turned off. I'd suspect the switch although I've never personally heard of this problem.
the ignition switch is new and i tried the old one and that gave me the same effect....switch ruled out. I'm going to try disconnecting the ignition terminal (it's a hitachi mini starter) and run a jumper between the wire and the terminal then pull it off and shut it down to see what happens. i'll let you know.
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