My 2004 F150 has a weird bug related to the seat belt sensor - it only reads the seat belt condition when the truck is first started, then ignores it the rest of the time. Not a big deal so long as I remember to buckle up before starting it. I tried to do the routine of turning off the chime, but because it doesn't read the seatbelt condition after the key is in the run position, it can't be performed. Likewise, if I start the truck buckled up and then unbuckle once its running, the seatbelt light does not illuminate on the dash.
Certainly an easy enough work around, though rather odd. Any body else ever hear of this? It's not a symptom of anything else, is it?
My dad's 04 did this exact same thing. If you didn't buckle the seatbelt before you started the truck, it would not recognize that you had buckled up. He never did anything about it and just made sure to buckle his belt before starting the truck.
I played it around with it more today. It seems like the sensor works once the trucks has been running and then turned off again. For a brief moment I thought I would be able to go through the disable chime procedure. Buckled and unbuckled 9 times but never got the air bag light to come on.
Would disabling the sensor be as simple as jumpering two leads together someplace?
I'm not sure about that on these trucks. I know that in my 2001 superduty, you just had to disconnect a harness that ran out of the carpet to a plug in the bottom of the seat. It was as simple as that.
I havn't looked under the seat in my f150, but it may have a plug too. I imagine though that if you unplugged it, it would set off some other warning like a light or something.