Invader 2 - electrics

[rocketman]

Hi Mark,
I think the only common factor with the circuits you are having problems with is the earth side.
Without someone has messed up the wiring in the past, the heater should only power up with the ignition switched on.
The hazards are powered through a different fuse and will be powered without ignition on.
Do not understand what you mean by demist, possibly heated rear screen?
What part of the world are you at?