its extremely rare for the module to be faulty, its fairly certain it will be a connection somewhere,as V64paul says its often the wiring in the seat area, there must be some there as they have pretentioners on the seat belt or stalk,a common problem.
The only issue you may have is by changing the module even if you cure the problem it will need resetting/programming.
Most independant garages have diagnostic/resetting equpment, they wouldnt survive without, local one to me charges £30.00+ vat.
Hymie, we checked a vehicle out a couple of days ago and someone had removed the dash fascia and put blobs of black silicone on each warning bulbs, quality...this had been done to sell the car.