UPDATE
I think the bulb has probably gone because the A/C light is not coming on either. I checked the wiring switch in the seatbelt plug is ok this is connected by the side of the seat to the wiring loom, alas one of the wires to the loom had snapped this is in a plastic corrugated protected section that has probably been caught in the seat runner. It would require the seat removing and possibly the transmission tunnel so I will live with it. I would still like to know if the bulbs are interchangeable or are they part of a module ?
