Well before you spend the money at the stealer, hook up a trailer and make sure all lights work as well as PDC when backing up. If not, the you need to code it!
For some reason some do and some don't! I think the cutoff is somewhere in 2004 production but not sure when?

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Current:
2017 640Xi Convertible
2011 Acura MDX
2018 Santa Fe

Past:
2013 Honda Accord
2008 Acura TL Tech.------2004 BMW X5 4.8is----2004 Acura MDX Tech
1994 BMW 525i.----------1994 Lexus 300 GS.----1994 Acura Legend GS
1991 Acura Legend LS.----1991 Honda Accord.----1991 300ZX twin turbo
1996 Buick Regal GS.-----1984 300Z 50th anniv.--2002 BMW X5
1982 280Z