mscwr00

My Yukon had this problem. Service Stabilitrak, check engine, trailer brake disabled... and many other messages which would repeat over and over. DingDingDings to boot! Speedometer and Tach would fluctuate wildly. Transmission would lockup in whatever gear you were currently in. Letting it sit for awhile (sometimes overnight) and/or removing the battery cable for 1 minute would eventually/sometimes reset the engine and it would run fine! This happened several times. We were lucky to limp into a dealership for diagnostics, but not a safe experience. Took it to 3 dealers and none could replicate the problem. Finally 4th dealer kept the car for a week and finally determined it was an intermittent TCM (Lost Communication) error. The new TCM fixed the problem and it has worked flawlessly for over a year now. I am perplexed that it was not easily diagnosed.