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 vehicle is equipped with the Tire Pressure Monitoring System. If a diagnostics check is needed between e-mails, push OnStar Additional Information, and an Advisor can run a check.

    See also:

    Removing the Flat Tire and Installing the Spare Tire
    1. Do a safety check before proceeding. See If a Tire Goes Flat on page 10‑58 for more information. 2. If the vehicle has a wheel cover, loosen the plastic nut caps with the wheel wrench. They ...

    TPMS Malfunction Light and Message
    The TPMS will not function properly if one or more of the TPMS sensors are missing or inoperable. When the system detects a malfunction, the low tire pressure warning light flashes for about one m ...

    Storing the Spare Tire
    WARNING The underbody-mounted spare tire needs to be stored with the valve stem pointing down. If the spare tire is stored with the valve stem pointing upwards, the secondary latch will not work prop ...