Now then Dave,
An earth can put on a false feed to your warning lights, this is why the appear to be on.
The thing i can suggest is that you clean all the contacts up in your lights, front and rear (all lamps/contatcs). On the Fords the most common problem used to be the back lights and the spade connector terminals, if they get 'furred up' white/green looking, this can cause and earth putting a positive feed onto the lamps. give them a gooc clean up and a smear of vaseline this will prevent the same happening again.

PS Have you shit your pants yet in that 280BHP RWD cossie yet????

Good Luck

Andi