Sorry read it wrong thought it was on on not off :oops:
Not someting silly like the bulb is it, have you checked for a voltage at the bulb, or a damaged earth wire
looking at the wiring diag for a 24v, ign light is fed from fuse point 5, with a white wire
the other side of the light should have a brown/yellow wire going to the generator panel, it passes through a snap connector that changes the wire to yellow just before the panel, that is connected to terminal E on the panel
what are the ammeters reading?