HI there,
There are a few possible scenarios here. There is a switch in the buckle to let the module know its latched
#1, is the seat belt buckle pigtail not connected to the wiring under the seat????
#2, did anyone have the seat out at anytime and maybe didn't connect the switch????
If both of these are ok, then its most likely the seat buckle assembly itself.
Allthebest, Paul