See also:

Diagnostics
OnStar Vehicle Diagnostics will perform a vehicle check every month. It will check the engine, transmission, antilock brakes, and major vehicle systems. It also checks the tire pressures, if the v ...

Engine Coolant Heater
Your vehicle may have an engine coolant heater. In very cold weather, 0°F (−18°C) or colder, the engine coolant heater can help. You will get easier starting and better fuel economy durin ...

How to Detect a Tamper Condition
If is pressed and the horn sounds, an attempted break-in occurred while the system was armed. If the alarm has been activated, a message will appear on the DIC. See Anti-theft Alarm System Messa ...