DJ Spencer said:
that is true, but only if the one cable is TSR. We use them in the music industy all the time. You would also use a similar cable on the back of a TiVo unit. It basically looks like a stereo headphone jack (TSR - Tip, Sleave - Ring).
So in essence, you are both correct. TSR is generally used to send a mono signal out to a processor, return the mono signal to the board, and have a ground in between.
No, it is not one cable, serial communication on automobiles is one wire. I did look under the passenger seat to see if Delphi, the company I worked for, was responsible for the passenger seat detection system and they weren't. It was kind of surprising because Delphi did do the detection systems for Ford, Jaguar, and Volvo.
But, to go back to my arguement, automobile serial communication can and is almost all done through one wire. If it is through two wires it is not because of a send and receive wire, it is because the communication can operate at two speeds depending on what each of the ECUs are talking to (Safety systems, drivetrain, entertainment, etc.). This is the way VW, GM, Ford, Volvo, Jaguar, Saab, Subaru, Nissan and many other manufacturers do it.
GM is implementing a LAN type of communication with three different speeds and the stereo is required for the warning chimes. If you don't have the stock stereo in the vehicle then the chimes will not work. My friend had to do this with his GMC Sierra.
