So I'm back on this buzz of trying to fix the light. I finally got a hold of another car/instrument cluster to test with. When I put my cluster into the other car the airbag light works without an issue. When I put their cluster into my car the airbag light fails to illuminate. So there's no issue with my cluster, the problem is deeper. Contrary to previous thoughts on this I don't believe the IKE lights up the airbag light by default, I believe the light is lit by the MRS4 unit as soon as it's powered on until it performs its tests. So either wire 21 on the IKE's X11175 is broken/shorted or the MRS4 unit is playing up. I'm inclined to believe it's the MRS4 unit at this stage so I'm going to cut it out and get a spare one somewhere. Anybody know how to code it?