I have an Audi A4 in my garage and if the footbrake light is on in the selector mechanism cover the car will start and go in gear fine but if that light is not on it will not start nor go in gear what controls that light in their what is it I need to check or replace. Someone please help have lost sleep for a week thinking about this really want it fixed and out of the shop

 

A little update on this Audi. As long as we sit and let it cool it will start and th footbrake light comes on? Not sure what could cause that to happen?