My 1993 Aerostar loses power when I turn the ignition key.

Hello. I have a '93 Aerostar that was running fine. All of a sudden I opened the door, had interior lights and seemed to have electrical, but when I turned the key all power died but I could hear a humming noise coming from somewhere by the driver's side door. I changed the battery, again had power when I opened the door, radio worked, lights worked, but when I turned the key I lost all power and again heard the humming noise. When I remove the neg connection on the battery, then put it on again, I have power until I turn the key. Has anyone seen this before? Any help on where to start would be appreciated. Thanks

What does the humming sound like? Is it like a door ajar tone or a sound coming from the ignition switch? Some models had a recall on the ignition switch.

Thanks for the reply.
It sounds like its coming from somewhere below the driver's side door. It's not from inside the vehicle or from the engine compartment.

if you loose all electrical power when you turn the ignition key to START, you could have a battery cable that is not making good contact with the battery pole, even though it LOOKS like it is making contact.

Make sure that both cable clamps are clean and the poles too. AND make sure they are tight. If you changed the battery, are the battery poles SMALLER and the cable clamps slightly too big for the poles?

I had that problem months ago, turned out it was the Negative Cable Clamp not making good contact with the Negative battery Pole. I replaced the clamp with a new, smaller diameter clamp and the problem dissapeared.