Special Application Services

○ Severe Commercial Use Vehicles Only: Lubricate chassis components every 5 000 km/ 3,000 mi.
○ Have underbody flushing service performed once a year.

    See also:

    Footnotes — Maintenance Schedule Additional Required Services — Normal
    a) Check all fuel and vapor lines and hoses for proper hook-up, routing, and condition. Check that the purge valve, if the vehicle has one, works properly. Replace as needed. b) Or every four years, ...

    Customer Assistance for Text Telephone (TTY) Users (U.S. and Canada)
    To assist customers who are deaf, hard of hearing, or speech impaired and who use Text Telephones (TTYs), GMC has TTY equipment available at its Customer Assistance Center. Any TTY user can communicat ...

    Compass
    The vehicle may have a compass in the Driver Information Center (DIC). ...