Jerry Acheson,
I think you have it pegged. I have never had one of Langdons HEI units, but from what I have read on this site, this typifies a module failure.
Joker can attest to this fact I'm sure.
I don't know how the modules are tested, but on the truck, they are subjected to hot and cold cycles and vibration. These are not friendly things for anything solid state.
As with anything sealed/potted that is electronic, it is a replacement game.
I think this HEI has only a 12 volt switched wire to it...if that has power when the key is on, looks like the culprit is the electro-brain box.
Stuart
