Automatic Transmission Operation - GMC Sierra Classic 2007 Owner's Manual

Automatic Transmission Operation

If your vehicle has an automatic transmission,
it features an electronic shift position indicator
within the instrument panel cluster. This display
must be powered anytime the shift lever is moved
out of PARK (P). See Fuses and Circuit Breakers
on page 596.
There are several different positions for your
shift lever.
Automatic Transmission
Allison Transmission
138
See "Range Selection Mode" later in this section.
PARK (P): This position locks your rear wheels.
It is the best position to use when you start
your engine because your vehicle cannot move
easily. If your vehicle has the Allison
Transmission
use PARK (P) when starting. The Allison
Transmission
hold the weight of commercial medium duty
trucks. Therefore, the Allison Transmission
larger parts than other automatic transmissions.
These larger parts may sometimes make a
clunking noise when the selector lever is moved
from DRIVE (D) or REVERSE (R) to PARK
(P). This is normal and there is no damage
occurring during these shifts. When parked on a
hill, especially with a heavy load, you may
notice an increase in the effort to shift out of Park.
See Torque Lock (Automatic Transmission)
under Shifting Into Park (P) (Automatic
Transmission) on page 169 for more information.
®
®
, with the Power Take-Off (PTO),
®
has a park pawl that is designed to
®
uses