Whenever I open my driver's door the chime comes on, even when the key has been removed from the ignition. I used to be able to "jiggle" the key/switch on the column and it would stop. Now it comes on and stays on until the door is closed. The dealer said the key switch was worn and the "clock spring" needed to be replaced, at a cost of $400. Does this sound reasonable? That's a lot of money for a 12 year old truck. If I can't fix it at a reasonable price I might just have to live with it, or unplug the chime itself, if that is possible.

 

The clock spring has nothing whatsoever to do with the chime, but that doesn't mean it's OK. They might have diagnosed some other problem as a defective clock spring.

But you can replace the lock cylinder yourself for <$30 (aftermarket) or <$100 (Ford/MotorCraft). Read these captions:

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RockAuto sells the kit for $50 (Std) to $58 (MC).

 

Had the same issue on Dad's 2001, the metal tab in the key cylinder was loose and always making contact, so your symptoms could have the same solution.

Easy fit to pull the key cylinder out, and remove the broken tab out of the cylinder tunnel.

JMC has an easy how to in post #10 of this thread, the same procedure that Steve83 posted above ( only his has pictures ). The pictures in the post above you need to remove the cylinder to check for the tab in the housing are pictures #5 & #6

https://www.f150online.com/forums/el...beep-beep.html

 

I pulled the lock cylinder and didn't see anything in the tunnel except a contact with 2 wires. I covered the contact with electrical tape. Problem solved. No dinging with the door open, and the alarm still comes on when the headlights are left on. Just doesn't alarm if I leave the key in the ignition. I'm happy. Guys, thanks for the help.