Strange beeping under dash? F150

Hello all,

So this weird beeping started from under the dashboard on my 99 f150.

Not sure what's causing it.. but it's really annoying.
When starting the truck, it beeps about 4-5 times, pauses then beeps again... does this about 3 or 4 times... then stops.

No warning lights, always wear seatbelts, airbags seem ok, no abnormal engine happenings... just the beeping.

Can anyone shed some light on whats going on?

You'll probably find that your Airbag indicator lamp isn't illuminating - I believe it should illuminate for a few seconds when the ignition is switched to the 'Run' position. If there's a fault in the system but the lamp isn't working then the system beeps instead, to alert you to the fault condition.

So the lamp should be replaced, following which the lamp will flash to indicate the diagnostic trouble code (DTC). This thread (http://www.automotiveforums.com/vbulletin/showthread.php?t=909625) in the Ranger forum explains how to interpret the flashing of the lamp, to obtain the DTC.