It might be "5 bucks worth of junk"...but the R&D costs a
fortune. Nobody understands this about electronics, and I dont think anyone ever will understand/appreciate what goes into them unless they actually get into the field themselves. I have only come to appreciate this much more as I design my truck electronic modules. I have literally hundred and hundreds of hours into designing/engineering/coding/testing/trial/error in my lockup controller for example....and my lockup controller doesnt even have to communicate on the truck's data bus! (so multiply that couple hundred hours by 5, at least, to write all the software to speak Class 2 to the rest of the truck)
Its NOT JUST A "SWITCH". You can make a "radio C2 to RCA input" cable....but its not gonna do diddly unless there is a factory auxiliary module (such as a remote denali/escalade CD changer, factory XM or factory rear-seat entertainment/DVD) telling the radio "yes, im here, you can enable the aux input".
The radio is not going to enable to input by itself if theres no factory device installed in the truck that will be using it, for obvious reasons.
Now, obviously, those aftermarket modules arent "a factory XM, cd changer, dvd box"...so what they have to do is design a mini computer in the module that makes the factory radio THINK its hooked up to a factory auxiliary module. It has to communicate with the rest of the truck, ALL of the modules, and speak ALL of the correct messages on the databus. If it sends out a wrong message on the data bus, it could do everything from accidentally make the driver side window go down, to even shutting the engine off.
So if you're making a module that talks on the databus, you damn well better make sure your software code is bulletproof and doesnt have any bugs/glitches. All of this debugging/testing/etc takes hundreds of hours, and the companies that are making these modules have to pay software engineers (who generally command a pretty good paycheck) full-time to design them.
And then theres the information about the Class 2 databus specific messages....its PROPRIETARY. IE, GM will not just give out the computer code that "makes the radio turn on the auxiliary input". You cant just take a factory XM module and "download the file, and then copy/paste into your own aux input widget". You have to either:
A) spend dozens of hours in the truck listening to the databus with your laptop, trying to decipher WHICH of the (hundreds of messages per second that pass over the databus) is the correct "enable aux input" message that the XM module is sending to the radio. Reverse engineering from scratch, basically. Like trying to break radio-transmission codes during world war II. Then, once you've found that, you have to build your aux-input modules extra operating software around that code, and make sure the software is stable and wont crash....which, as I said before, if your aux input module crashes, it could do really bad things to the truck.
B) buy the white-papers from GM. I think they sell them for like $50,000/year
So you can see that, sure...might physically be "5 dollars of junk", but the R&D and software in that module is
NOT "5 dollars of junk".
Hopefully that will help people better understand WHY they are paying $50 for "just an aux input"
Ben
