Excellent information. The serial bus on modern vehicles is going to prove to be a weakness once a little age and wear sets in. You may have just encountered one of those instances. I see this on older industrial controls all the time, and now that the automotive industry has espoused itself to the concept, it has unknowingly opened a can of worms. You automotive professionals had better sharpen up on electronics technology quickly, since the tip of the iceberg is beginning to be exposed. Industrial electronics have used (and mostly abandoned) the serial communications protocols since the '60s. Some still cling to it, but most have moved forward to optical or ethernet.