Volt light on dash

[MyType]

Hi - I'm new to this forum but I have had my '85 T-Type for a long time. A week ago I upgraded my speedometer to a 145mph decal and had the speedometer head recalibrated. Everything has worked great over the past week. Tonight I was out cruisin in the car for about half hour and when I turned off the engine, the Volt idiot light lit up. It is not on when the engine is running, it turns on only after I turn off the engine. I'm concerned someing is drawing current from somewhere, so I disconnected the battery. Does anyone have any thought on where I should start looking?
Curt

 

[MyType]

Well, I just thought I'd let everyone know I fixed my problem. It was just a coincidence that the problem popped up just after I upgraded my speedo, the problem had nothing to do with my dismantling of the dash.
My alternator was bad, and was wired so the Volt warning light would come on after you shut off the car, rather than coming on when the car was running. With the replacement alternator, everything is much better.