The seat belts in a Subaru WRX have been replaced with 4 Point Racing Harnesses. The air bag light now stays on. Does this mean the air bags are inoperable or will they still deploy in case of an accident?
Inoperable. The system has shut itself off, because the normal “Person seated and buckled in” signals are gone.
If this car is driven on the street, I would suggest putting it back the way it was for safety. Three point harness with the airbag is safer than four point without the airbag. If this is an off road race car and your sanctioning body requires a four point harness, you will have to live without the airbag. It’s not designed to work with this setup, anyway.