The steering wheel position sensor may fail, resulting in the service stability message being displayed.Google+
Car Problem Reports
Buick Lucerne Steering Wheel Position Sensor May Fail
Buick Lucerne Problem
The Stablity Track light comes on constantly. There are times when driving down the highway and my vehicle would simply drop down to 30 mph. I was able to have my vehicle shipped to the dealership and the Stability Track sensor was bad. Replaced it twice. And I'm still having the same problem.