1st...Thanks to all the guys on this site
2nd...Sorry for the long sad story... LOL

I was removing the rear seat in my new-to-me 05 FX4 SC and I had the front seats pushed all the way forward. When I was finished I was powering the driver seat back and it slowed down, strained a bit and then pop...it sped back up and back it went. Well a few minutes later I hopped in to go somewhere and my airbag light was blinking!!!! After a few minutes on this site I decoded the flashes (five pause one=5-1) and learned the following...

Code 51
Pinpoint Tests


Air Bag Diagnostic Monitor Internal Thermal Fuse -- Fuse Blown Due to Intermittent Short to Ground


Normal Operation

Note:
The air bag diagnostic monitor contains an internal thermal fuse that is not serviceable. The thermal fuse is controlled by a computer inside the air bag diagnostic monitor. The computer will blow the thermal fuse whenever a short on the deployment circuits occurs. The thermal fuse does not blow because of excessive current flowing through it. DO NOT attempt to jumper out the thermal fuse with a circuit breaker or any other type of fuse.

Note:
DO NOT install a new air bag diagnostic monitor until the short has been located and corrected. If a short to ground has not been located and corrected, then the short to ground is intermittent and IS NOT PRESENT AT THIS TIME. Installing a new air bag diagnostic monitor with an intermittent short in the system will result in blown air bag diagnostic monitors and repeat repairs.

The air bag diagnostic monitor measures the voltages at the diagnostic monitor connector pins. When certain air bag deployment wires are shorted to ground (heavy lines illustrated in the schematic below), the supplemental air bag restraint system may become susceptible to unwanted deployment of the air bag(s). The air bag diagnostic monitor senses a short to ground on any of these circuits and helps prevent unwanted air bag deployant by blowing the diagnostic monitor thermal fuse. Blowing this fuse removes all power (battery and back-up power) from the air bag deployment circuits. While the short to ground exists, the monitor will flash code 13. If the short to ground is intermittent and temporarily corrects itself, the air bag diagnostic monitor will flash code 51.

Note:
If the short to ground returns, the high priority code 13 will flash instead of 51.

If the air bag indicator is flashing code 51 and a short to ground has not been serviced, this means that an intermittent short to ground exists in the supplemental air bag restraint system. The air bag diagnostic monitor should be replaced only after repairs to the intermittent short have been completed.

Some service tips for finding an intermittent short to ground are:

(1) Consult OASIS (Restraint Systems Service Code 104000) for up-to-date diagnostics and descriptions of wiring concern locations for the vehicle (VIN number) you are working on. OASIS is updated daily using concern descriptions from engineering and Dealership Service sources.

(2) Inspect wiring and harness in areas where they pass through or are located next to metal components (i.e., engine compartment bulkhead, body sheet metal, component mounting brackets, etc.).

Now I said Oh no...I juse bought this truck as is and now I have to replace this module!!! GREAT...Well remember the pop.....???

I decided to investigate the pop so I searched how and pulled out the front center seat cushion...and what i FOUND WAS... The seat belt receptical has wires running into it...they are affixed via a white plug AND the seat belt receptical wires had become hung on the center seat belt buckle (that was logded between the seats) and had pulled out of one side of the plug... So I pushed them back in...taped it up real well so they would not come out... moved the wires inboard the seat so they would not get caught again...and VOILA...the light went out......and has not returned......

Hope this helps someone getting the same code...I also read there is a 1-3 code that appears...I did not get it...

Again thanks to everone else on this site for saving me an $85+ diagnostic fee!!!!