tow hitch wiring harness

[krnnerdboy]

I'm towing my z4m to streets of willow this weekend so I thought I ought to get my trailer wiring harness programmed. I gave Savage BMW a call and they quoted me $400 SO I called Crevier BMW and they quoted me $160, which is the usual price on the forums...I get there and pick up my loaner and later get a call saying it will cost $400 and some change if they run in to issues. Needless to say I went and picked up my x5 and brought it home to look for a quick fix for a non programming harness. I give the local uhaul a drop and see that they have one in stock for $50. 45 min later I had it installed and verified it was working w/o any error lights!

Now my question is, there seems to be some question whether the harness programming also inputs a tow mode for the tranny when towing. Is there a definitive answer to this?