It is precisely for this reason that the cost of installing a(n) (aftermarket?) hitch can become prohibitive. My dealer has warned me that they'll do the coding, but it may take up to 2 hrs or more because ALL modules need to be updated in order for it to be done properly. At $100+/hr this adds up quickly. I believe that the coding is already included as part of a dealer OE install.
Originally Posted by invisihitch
... In the meantime, I want to offer one caution to the DIY coders for adding the hitch option: If other modules are not brought up to the latest revision before you add the hitch option, you MAY end up with non-functioning brake lights on the trailer.