A Hummer major service is a comprehensive maintenance procedure that typically includes all of the services provided in a minor service, as well as additional checks and replacements of parts that are subject to wear and tear over time.

Most manufacturers recommend having a major service done every 12 months or 20,000 kilometers, whichever comes first. However, the recommended service intervals can vary depending on the make and model of your Hummer .

A typical major service includes an oil and filter change, a full inspection of the brake system, a replacement of spark plugs, a replacement of air filters, a check and replacement of various fluids such as coolant and brake fluid, a visual inspection of the suspension and steering system, and a check of various components such as the battery, belts, and hoses.

While it is possible to perform some aspects of a major service on your Hummer yourself, it is recommended that you seek the assistance of a professional mechanic who has the necessary tools and expertise to perform the service properly.

A major service typically takes between 3-4 hours to complete, depending on the make and model of your Hummer and the extent of the service being performed.

The cost of a major service can vary depending on the make and model of your Hummer and the specific services being performed.