Active Fuel Management; Automatic Transmission Operation - Chevrolet 2009 TrailBlazer Owner's Manual

Active Fuel Management™

The vehicle's V8 engine may have Active Fuel
Management™. This system allows the engine to
operate on either all or half of its cylinders, depending
on driving conditions.
When less power is required, such as cruising at a
constant vehicle speed, the system will operate in the
half cylinder mode, allowing the vehicle to achieve better
fuel economy. When greater power is required, such
as accelerating from a stop, passing, or merging onto a
freeway, the system will maintain full-cylinder operation.
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Automatic Transmission Operation

P (Park): This position locks the rear wheels. It is the
best position to use when you start the engine because
the vehicle cannot move easily.
There are several different
positions for the gear shift
lever.