Headlights won't shut off!!

Myterious situation with the head lights on my 90 Ford Aerostar van.

Noticed the high beam indicator light on the dask and the headlights were on the other day and this was with the switich in the off position.

Came home and parked it and the headlights went out when I shut the car off. Now they stay on even with the car shut off and the key out of the ignition. I have to unhook the battery cable to preserve the battery.

Any ideas as to what is going on here. I checked the Chilton manual for the wiring schematic and it looks basically bullet proof.

How is the power getting to the headlites with the switch off?

Any help would be greatly appreciated.

Thanks

Martin

there is a module right beside the battery unhook it and see if the lights will go off when the key is off.you have to move the battery to work on it.

erm the switch may be faulty or mabey theres a short?