Steve Routledge

Hi I have a x350 09 2.7D. Problem started with an amber warning light and message stating park brake fault. I stopped to try and reset but after turning ignition off and back on, engine started but gear change was stuck in D. Called AA breakdown who said that the diagnostic was showing brake light switch was faulty. Brake lights were working!! AA guy jury rigged the gear selected interlock so that I could drive home. Has anyone had this issue and where is the switch pls steve