4 sets of 5 beeps
 

4 sets of 5 beeps started while driving down the road. This is a 1994 Ford F150 XL 4.9. It made some other sounds that reminded me of a old dial up modem. Not all the time. Started when I was 3 miles from home. At first I thought it was the radio. I turned it off. After a few minutes another set of beeps. Started for the house. and started to smell burning like wiring. Got it towed to the house. Checked for blown fuses or signs of hot or melted wiring. I found none. The fluids are fine and the only work done on it was a new computer module a few months ago. Any help or ideas will be put to use.

Could the sound you are hearing be coming from a seat belt chime?

No it's not from the seat belt warning. Later in the day it changed to 5 beeps 5 times. All I have to do now is put the key in the ignition switch. and it starts the beeps.

If I recall correctly, the beeps used to come on if the key was left in the ignition and a door was opened.. I would be inclined to look into one of the door switches being stuck as if a door was open.Will check a little further into that.

5 sets of 5 beeps.
 

I haven't checked the door switches. Will do that for sure. Hope that is it. I'm worried about even starting it. It's my only means of transportation. Sure do like getting the help.

There are a few comments that seemed to confirm the problem was in the seat belt system, warning that something was not working correctly.
Will hopefully locate a wiring diagram that may reveal what and where that 5 time warning beep originates.

5 sets of 5 beeps on 94 f150 4.9
 

I have checked the door switches. They are not the problem. It has been raining and to cold to be out working on it lately. I put the key in the ignition and the 5 beep sets started right up. Removed the keys and that didn't stop the beeps. I kept checking on it off and on. After six hours it was still doing the beeps. I found the source of the beeps coming from a box under the dash with a couple of big wire harness connections If I open the box is anything going to fly out or fall apart on me? Still looking for the solution.
https://cimg8.ibsrv.net/gimg/www.for...203770e0c4.jpg
The box with wiring harness connections and makes the beep noises

Did you find a solution? Having the same problem. It happened after getting upholster work done and they had to remove the seatbelt (attached too top of seat)