2008 CHEVROLET SILVERADO automatic transmission

Keys...............................................................2-3
Remote Keyless Entry (RKE) System................2-4
Remote Keyless Entry (RKE) System
Operation...................................................2-5
Remote Vehicle Start......................................2-7
Doors and Locks............................................2-10
Door Locks..................................................2-10
Power Door Locks........................................2-10
Delayed Locking...........................................2-11
Programmable Automatic Door Locks..............2-11
Rear Door Security Locks..............................2-11
Lockout Protection........................................2-12
Rear Doors..................................................2-12
Tailgate.......................................................2-13
Windows........................................................2-15
Manual Windows..........................................2-15
Power Windows............................................2-16
Power Sliding Rear Window...........................2-17
Sun Visors...................................................2-18
Theft-Deterrent Systems..................................2-18
Content Theft-Deterrent.................................2-18
PASS-Key
®III+ Electronic Immobilizer.............2-20
PASS-Key®III+ Electronic Immobilizer
Operation.................................................2-20Starting and Operating Your Vehicle................2-22
New Vehicle Break-In....................................2-22
Ignition Positions..........................................2-22
Retained Accessory Power (RAP)...................2-24
Starting the Engine.......................................2-24
Fast Idle System..........................................2-25
Adjustable Throttle and Brake Pedal................2-26
Engine Coolant Heater..................................2-27
Active Fuel Management™.............................2-28
Automatic Transmission Operation...................2-28
Tow/Haul Mode............................................2-34
Four-Wheel Drive..........................................2-36
Parking Brake..............................................2-50
Shifting Into Park..........................................2-51
Shifting Out of Park......................................2-53
Parking Over Things That Burn.......................2-53
Engine Exhaust............................................2-54
Running the Vehicle While Parked..................2-54
Mirrors...........................................................2-56
Manual Rearview Mirror.................................2-56
Automatic Dimming Rearview Mirror
with OnStar
®, Compass and Temperature
Display....................................................2-56
Automatic Dimming Rearview Mirror with
Compass and Temperature Display..............2-58
Section 2 Features and Controls
2-1

How long should you keep the coolant heater plugged
in? The answer depends on the outside temperature, the
kind of oil you have, and some other things. Instead of
trying to list everything here, we ask that you contact your
dealer/retailer in the area where you will be parking your
vehicle. The dealer/retailer can give you the best advice
for that particular area.
Active Fuel Management™
Your 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 the 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 your vehicle to achieve
better fuel economy. When greater power demands are
required, such as accelerating from a stop, passing,
or merging onto a freeway, the system will maintain
full-cylinder operation.
If your vehicle has an Active Fuel Management™
indicator, seeDIC Operation and Displays (With DIC
Buttons) on page 3-57orDIC Operation and Displays
(Without DIC Buttons) on page 3-63for more information
on using this display.
Automatic Transmission Operation
If your vehicle is has an automatic transmission,
it has an electronic shift position indicator within the
instrument panel cluster. This display comes on when
the ignition key is turned to the ON/RUN position.
There are several different
positions for the shift lever.
Hydra-Matic
®4-Speed
Automatic Transmission
2-28

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 the engine because
your vehicle cannot move easily. When parked on a hill,
especially when the vehicle has a heavy load, you might
notice an increase in the effort to shift out of Park. See
Torque Lock (Automatic Transmission) underShifting
Into Park on page 2-51for more information.
{CAUTION:
It is dangerous to get out of your vehicle if the
shift lever is not fully in PARK (P) with the
parking brake rmly set. Your vehicle can roll.
CAUTION: (Continued)
CAUTION: (Continued)
Do not leave your vehicle when the engine is
running unless you have to. If you have left the
engine running, the vehicle can move suddenly.
You or others could be injured. To be sure your
vehicle will not move, even when you are on
fairly level ground, always set your parking
brake and move the shift lever to PARK (P).
SeeShifting Into Park on page 2-51. If you
are pulling a trailer, seeTowing a Trailer on
page 4-55.
{CAUTION:
If you have Four-Wheel Drive, your vehicle
will be free to roll — even if your shift lever
is in PARK (P) — if your transfer case is in
NEUTRAL. So, be sure the transfer case is in a
drive gear, Two-Wheel Drive High or Four-Wheel
Drive High or Four-Wheel Drive Low — not in
NEUTRAL. SeeShifting Into Park on page 2-51. Allison Transmission
®or Hydra-Matic®6-Speed
Automatic Transmission
2-29

Your vehicle has a shift stabilization feature that adjusts
the transmission shifting to the current driving conditions
in order to reduce rapid upshifts and downshifts. This shift
stabilization feature is designed to determine, before
making an upshift, if the engine is able to maintain vehicle
speed by analyzing things such as vehicle speed, throttle
position, and vehicle load. If the shift stabilization feature
determines that a current vehicle speed cannot be
maintained, the transmission does not upshift and instead
holds the current gear. In some cases, this could appear
to be a delayed shift, however the transmission is
operating normally.
Your vehicle’s transmission uses adaptive shift controls.
Adaptive shift controls continually compares key shift
parameters to pre-programmed ideal shifts stored in the
transmissions computer. The transmission constantly
makes adjustments to improve vehicle performance
according to how the vehicle is being used, such as with
a heavy load or when temperature changes. During this
adaptive shift control process, shifting might feel different
as the transmission determines the best settings.
When temperatures are very cold, the Allison
Transmission
®and Hydra-Matic®6-Speed transmission’s
gear shifting could be delayed providing more stable
shifts until the engine warms up. Shifts could be more
noticeable with a cold transmission. This difference in
shifting is normal.MANUAL MODE (M):This position, is available on
vehicles with the Allison Transmission
®or Hydra-Matic®
6-Speed transmission. It lets drivers select the range
of gears appropriate for current driving conditions.
If your vehicle has this feature, see Range Select
Mode (Allison Transmission
®or Hydra-Matic®
6-Speed transmission) later in this section.
THIRD (3):This position is also used for normal driving.
It reduces vehicle speed more than DRIVE (D) without
using the brakes. You might choose THIRD (3)
instead of DRIVE (D) when driving on hilly, winding
roads, when towing a trailer, so there is less shifting
between gears and when going down a steep hill.
SECOND (2):This position reduces vehicle speed even
more than THIRD (3) without using your brakes. You can
use SECOND (2) on hills. It can help control your speed
as you go down steep mountain roads, but then you
would also want to use the brakes off and on.
If you manually select SECOND (2) in an automatic
transmission, the transmission will start in second gear.
You can use this feature for reducing the speed of the
rear wheels when you are trying to start your vehicle
from a stop on slippery road surfaces.
2-31

To use this feature, do the following:
1. Move the shift lever to the MANUAL MODE (M).
2. Press the plus/minus buttons, located on the
steering column shift lever, to select the desired
range of gears for your current driving conditions.
When MANUAL MODE (M) is selected a number
displays next to the M, indicating the current gear.
This number is the highest gear that can be used.
However, your vehicle can automatically shift to lower
gears as it adjusts to driving conditions. This means
that all gears below that number are available. When
FIFTH (5) is selected, FIRST (1) through FIFTH (5)
gears are automatically shifted by the vehicle, but
SIXTH (6) cannot be used until the plus/minus button
located on the steering column lever is used to change
to the gear.
Grade Braking is not available when the Range
Selection Mode is active. SeeTow/Haul Mode on
page 2-34While using the Range Selection mode feature, cruise
control and the Tow/Haul mode can be used.
Notice:Spinning the tires or holding the vehicle
in one place on a hill using only the accelerator
pedal may damage the transmission. The repair will
not be covered by your warranty. If you are stuck,
do not spin the tires. When stopping on a hill,
use the brakes to hold the vehicle in place.
Low Traction Mode
If your vehicle has the Allison Transmission®,orthe
Hydra-Matic®6-Speed Automatic Transmission, it has a
Low Traction Mode that assist in vehicle acceleration
when road conditions are slippery, such as with ice or
snow. While the vehicle is at a stop, select the second
gear range using the Range Selection system. This will
limit torque to the wheels after it detects wheel slip,
preventing the tires from spinning.
2-33

Tow/Haul ModeIf your vehicle has an automatic transmission, it
has a tow/haul mode. If your vehicle has an Allison
or Hydra-Matic
®6-speed automatic transmission see
“Tow/Haul Mode (Allison or Hydra-Matic®6-Speed
Automatic Transmission®) following. The tow/haul
mode adjusts the transmission shift pattern to reduce
shift cycling, providing increased performance, vehicle
control, and transmission cooling when towing or hauling
heavy loads.
The selector button is located on the end of the shift
lever. Turn the tow/haul on and off by pressing the
button. When the tow/haul is on, a light on the
instrument panel cluster will come on.
SeeTow/Haul Mode Light on page 3-54for more
information.
Also see Tow Haul Mode underTowing a Trailer on
page 4-55for more information.
2-34

Tow/Haul Mode (Allison Transmission®
or Hydra-Matic®6-Speed Automatic
Transmission)
If your vehicle has an Allison or Hydra-Matic®6-speed
automatic transmission®, it has a tow/haul mode.
The tow/haul mode adjusts the transmission shift pattern
to reduce shift cycling, providing increased performance,
vehicle control, and transmission cooling when towing
or hauling heavy loads.
Turn the tow/haul mode on and off by pressing the
button, located on the end of the shift lever. When the
tow/haul is on, a light on the instrument panel cluster will
come on.
SeeTow/Haul Mode Light on page 3-54for more
information.
Also see “Tow Haul Mode” underTowing a Trailer on
page 4-55for more information.
2-35

Grade Braking (Allison Transmission®
or Hydra-Matic®6-Speed Automatic
Transmission)
The Grade Braking shift modes can be activated by
pressing the button on the end of the shift control lever.
While in Range Selection Mode, Grade Braking is
deactivated allowing the driver to select a desired
range of gears.
Grade Braking is only active while the Tow/Haul Mode is
selected and you are not in the Range Selection Mode.
See “Tow/Haul Mode listed previously andAutomatic
Transmission Operation on page 2-28for more
information on the Range Selection Mode. Grade Braking
assists in maintaining desired vehicle speeds when
driving on downhill grades by automatically implementing
a shift schedule that utilizes the engine and transmission
to slow the vehicle. This reduces wear on the braking
system and increases control of the vehicle. Grade
Braking monitors vehicle speed, acceleration, engine
torque and brake pedal usage. Using this information,
it detects when the truck is on a downhill grade and the
driver desires to slow the vehicle by pressing the brake.
See the diesel supplement for information on Cruise
Grade Braking.
Also seeTowing a Trailer on page 4-55for more
information.
Four-Wheel Drive
If your vehicle has Four-Wheel Drive, you can send the
engine’s driving power to all four wheels for extra traction.
To get the most satisfaction out of Four-Wheel Drive, you
must be familiar with its operation. Read the part that
follows before using Four-Wheel Drive. See the
appropriate text for the transfer case in your vehicle.
Notice:Driving on clean, dry pavement in
Four-Wheel-Drive High or Four-Wheel-Drive Low for
an extended period of time may cause premature
wear on your vehicle’s powertrain. Do not drive on
clean, dry pavement in Four-Wheel-Drive High or
Four-Wheel-Drive Low for extended periods of time.
While driving on clean dry pavement and during tight
turns, you may experience vibration in the steering
system.
Front Axle
The front axle engages and disengages automatically
when you shift the transfer case. Some delay for
the axle to engage or disengage is normal.
2-36