My ode's are actually kilometers. Not sure how to convert it to odes though. My tachometer actually measures revolutions per minute, even though it should measure tackies, and my speedometer is actually in km/h, not actual speed units like in the UK, where you speak a different language...what is it called? English or something?
Sorry, couldn't resist.
Your brake light circuit should stay live all the time anyways. There is probably a relay that is stuck in the closed position... if you can find it, yank it and swap in the same relay from a different circuit. Sorry, but like I said, I don't own an E36, but that's my suggestion. Maybe someone will back me up, or shoot me down.