Strangeness with lights. Uch?

[jefinabox]

Hello,
After sitting about a year I've tried to get my 172 cup going again. Everything works until I start the engine, then the headlights, sidelights and indicators stop working. They all work with the ignition on but not the engine. Sometimes they work for a few seconds after the engines started, then you hear the relay click and it'll all turn off.

I'm thinking uch but does anybody have any better ideas?

Thanks