Dealing with my endless lack of brakes in a 300CD, i changed the master cylinder and have some improvement, but just noticed that THE BRAKE TAIL LIGHTS ARE ON WHENEVER THE IGNITION SWITCH IS IN THE RUN POSITION, WHETHER THE BRAKES ARE STEPPED ON OR NOT! I jacked up each wheel to see if it spun freely, both with and without the engine running, and all four spin freely. Tried pulling the electrical connectors off the reservoir, made no difference. Am baffled, and wondering if there is some connection with the brakes working so poorly despite nearly every part in the system having been replaced, and repeated attempts at bleeding the brakes. Where is the switch that controls those lites? Thanks!