I take it youve used the wiring from under the old original seat? If so and its still flashing. then maybe the airbag system checks the airbag module in the seat itself which then sends a ' message ' so to speak back to the control units which then disables the light? Bit like when the air bags deployed the light stays on or flashes ( cant remember what mine did when i barrel rolled my ST170 lol ) but i think the airbag unit in the seat sends a message back to the control unit.. sort of self checks itself thent he light goes out..