407 Coil Failure

[Julian Caples]

The 407 does have a relay

you must have either a relay or a diode in the feed from the starter solenoid or you will have power fed (at about 8-9v) from the coil feed back to the starter after the engine has been started - this is unlikely to be a good thing

the other method for bypassing the ballast during starting is a separate circuit independently switched from the ignition key (i.e. when turning the key to the 'start' position, it activates two independent circuits - one for the starter solenoid and another that bypasses the ballast)

John's chevy installation must have a diode or relay in the solenoid (i.e. specific terminal for a ballast bypass that does not allow feed back to the solenoid)

regards

Julian