Couple of years ago my son's truck had to have an new alternator. Took it to a repair shop and had them replace. My son told me that when he went to pick up the truck the ABS light was on and when he turned the vehicle off and took the keys out of the ignition and opened the door, the dinger was going off as if the keys were still in the ignition. Of course doesn't bother my son, but I'm working on replacing a window motor in his door and this dinger is a major pain. Any suggestions on how I can stop this dinger? 1998 F150

 

disconnect the battery

 

my 06 has given me the keys in the ignition "ding" when getting out of my truck with keys in hand. I put the key back in and took it back out and it stopped. I'd assume there is something in the ignition switch that can get stuck into believing the key is there. Maybe a replacement ignition switch would help you?

 

Take the gin switch out, the little clip that is in there ( to make contact with the key in ) must likely is broken. Dad's 2001 had this happen.

Here is a thread on the topic :
https://www.f150online.com/forums/el...beep-beep.html

Don't be shocked if the part falls out when you pull the ign cylinder

 

this may sound stupid, but adjust the steering wheel height. Sometimes the switch gets activated for strange reasons. The other idea is with the keys out wiggle the ignition and try to push and pull the ignition towards the steering column not too hard, just a little.