Steady beeping on startup

[Walter]

i have a steady beeping on startup for 30 seconds or so and then it stops. It doesn't happen everytime but most of the time. 2000 Expedition Eddie Bauer 2WD.

5.4 liter V8 SOHC 16V
RWD
Std towing 5900 lbs
Max towing 8300 lbs
GVWR 7000 lbs
7.5" clearance
Eddie Bauer 2WD
Disc brakes 4-wheel ABS
Tran: 4-speed auto OD
255/70R16
Wheelbase 119.10"
Curb. Weight 4833 lbs

 

[stamp11127]

I shortened the thread title to make it more descriptive of the problem.
There are multiple items that can cause the beeping. Are there any warning lights on while this is happening?

 

[Walter]

Tks for your reply! No none.