Okay I know there are a lot of topic on this, but my problem is a bit different from things I've read.

I have 2006 single cab stx and the little orange airbag guy below the speedometer has been on over a year and a half and he always flashes a code 51, but I've never worried about it.

About a month ago I started occasionally getting the 5 beeps 5 times, and now it does it more frequently but not every time. The Passenger Airbag Light above the radio works properly. It comes on when I start the truck and then goes off. When I put weight on the seat (usually my Jack Russell who only weighs 14lbs) it turns on and stays, and if the seat belt is buckled with no weight it also stays on. This is proper function correct ?

I've tried things I've read from replacing or cleaning up the crash sensor in front of the radiator, even cleaned the connections under the seats with contact cleaner, pulled fuses and none of them are blown. Are the code 51 and the beeping alarm somehow connected ? I'm completely stumped and any ideas are greatly appreciated !

 

Here is a link to a thread where I recently fixed a "Code 51" on a 1995 Thunderbird in my possession. Code 51 means the Airbag Diagnostic Monitor detected a short to ground in one of several air bag circuits, the thermal fuse was blown, but now the short is not present so it was a intermittent short. You should find the short before replacing the ADM, which I did attempt to do ..... but mine was not a short so much. In my case it was a weak negative battery terminal clamp and momentary failure while ignition was in start position also reset my clock and after a second episode .... it all made sense. I explained what happened in my case in that link. I had a hard time finding good info on it on the net, but when I did it was in a thread about Ford Probes as I recall. Check it out here. All posts there in that thread as of this moment are "mine".

I am in no way suggesting that anyone reading this should do this.

Also, here's a link here that may help explain. Airbag flashing 5-1???? - F150online Forums