The steering wheel position sensor may fail, resulting in the service stability message being displayed.
Car Problem Reports
Cadillac STS Steering Wheel Position Sensor May Fail
Cadillac STS Problem
Average Mileage: 63,000 mi (31,000 mi - 95,000 mi)
Visitor, 2005 Cadillac STS, 31,000 mi
Squeeking noise when turning wheel. Service stability light comes on.
stability control and brake assist light up. It seems that this is a problem with most cadillac models...