Quote:
Originally Posted by TerminatorX5
interesting - somehow, a trailer module was working fine in the '06 without any programming... i installed it about 6 months ago... maybe because it is a 4.8?
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Up to 2003, the instructions from BMW made no mention of coding. On this board, many of us installed hitches (I installed two OE hitches myself, one was a 2007 X3, same trailer control module) with no issues. Starting in 2004, posters began to complain that their trailer modules did not function correctly, and BMW developed a coding solution. All of that history is documented on this and other boards. The published service instructions changed. They then said to code (or flash) the vehicle. This procedure does not install code for the lights or the trailer stability control (both of which worked fine without coding on prior and some later models) it simply overcomes a problem by which the vehicle does not recognize the trailer wiring module. I don't know the particular steps, but they are documented here. I just don't have reason to recall what the GT-1 or similar instructions were. There was a specific set of steps to follow, I do remember that. It doesn't happen in all cases. If you plug it in, and it works, great. But the reason that BMW changed the service instruction is that in some cases, coding was required.
Opinions vary on why it happens to some and not other vehicles. Personally, I think it is because of the specific combination of various modules and options installed on a specific vehicle. I can't prove that, it is just an educated guess. It may be that a newer version of the vehicle software was released at some point that just doesn't look for the trailer wiring module, ie faulty vehicle software. Can't say. But the service instructions continue to say that coding is required, leading me to believe that it wasn't confined to a specific batch, but is rather dependent on the individual vehicle consist.
Your sample of one is no doubt correct, but that doesn't over rule the BMW service instructions or the history of many who have had to have their vehicles coded post 2004.