2005 GMC SIERRA cooling

Tow/Haul is a feature on automatic transmission
equipped vehicles that assists when pulling a heavy
trailer or large or heavy load. Tow/Haul mode adjusts the
transmission’s shift pattern to reduce shift cycling,
providing increased performance, vehicle control, and
transmission cooling when towing or hauling heavy loads.
If your vehicle is equipped with an Allison
®transmission,
you may have both Tow/Haul mode and overdrive
disable. See “Tow/Haul Mode” underTowing a Trailer
on page 4-68for more information.
Grade Braking
(Allison Transmission®Only)
Grade braking uses the engine and transmission to slow
a loaded vehicle on hills in addition to using the
brakes, saving on brake wear and increasing vehicle
stability. The Allison Transmission
®, when sensing
the driver’s desire to slow down while driving downhill,
will automatically shift to the next lower gear range
to assist in slowing down the vehicle. Grade braking is
active and automatic both in Tow/Haul mode and
normal shift mode. Grade braking is more aggressive
when in Tow/Haul mode and can automatically downshift
to SECOND (2), which is different than grade braking
while in normal shift mode where automatic downshifts
are limited to FOURTH (4).The tachometer for both the diesel and gasoline engine
shows a dashed red zone and a solid red zone. The
dashed red zone indicates where a transmission
shift occurs for full engine power. When using grade
braking, the transmission’s shift point is adjusted to just
prior to the solid red zone, providing the benet of
additional engine braking.
Grade braking driving within the dashed red zone is
normal, both the diesel and gasoline engine have been
designed for this grade braking feature. Do not allow
the engine to go into the solid red zone. Apply the
vehicle’s brakes for a short time to slow down if you are
driving on a long hill and the tachometer needle
enters the solid red zone. SeeTowing a Trailer on
page 4-68for more information.
2-30

6(Floor):This setting directs most of the air through
the oor outlets, and the rest of the air is divided
between the windshield defroster outlets and the side
window defroster outlets.
W(Defog):Airow is delivered through the oor
outlets, the windshield defroster outlets and the side
window defroster outlets. The air ow can be divided
between oor and defrost depending upon where
the knob is placed between the settings.
1(Defrost):This setting directs most air through the
windshield defroster outlets, side window defroster
outlets and some through the oor outlets.
Dual Climate Control System
With this system you can control the heating, cooling
and ventilation for your vehicle.
9(Fan):Turn the left knob clockwise or
counterclockwise to increase or decrease the fan speed.
Turn the knob to the off position to turn off the fan. If
the knob is in off, outside air will still enter the vehicle
and will be directed based on the position of the
mode knob. The temperature can also be adjusted
using the temperature levers.
Turn the right knob clockwise or counterclockwise to
direct the airow inside of your vehicle.
3-22

Dual Automatic Climate Control
System
With this system, you can control the heating, cooling
and ventilation in your vehicle. Your vehicle also
has a ow-through ventilation system described later in
this section.
You can select different climate control settings for the
driver and passengers.
Driver’s Side Temperature Knob
The driver’s side knob is used to adjust the temperature
of the air coming through the system on the driver’s
side. The temperature can be adjusted even if the
system is turned off. This is possible since outside airwill always ow through the system as the vehicle is
moving forward unless it is set to recirculation mode.
See “Recirculation” later in this section.
Turn the knob counterclockwise or clockwise to lower or
increase the cabin temperature. The display will show
the temperature setting decreasing or increasing and an
arrow pointing to the driver will be displayed under
and to the left of the temperature setting.
Passenger’s Side Temperature Knob
The passenger’s side knob can be used to change the
temperature of the air coming through the system
on the passenger’s side of the vehicle. The temperature
can be adjusted even if the system is turned off. This
is possible since outside air will always ow through the
system as the vehicle is moving forward unless it is
set to recirculation mode. See “Recirculation” later in
this section.
Turn the knob counterclockwise or clockwise to lower or
increase the cabin temperature. The display will show
the temperature setting decreasing or increasing and an
arrow pointing to the passenger will be displayed
under and to the right of the temperature setting.
The passenger’s temperature setting can be set to
match the driver’s temperature setting by pressing and
holding the AUTO button for four seconds. Both the
driver and passenger arrows will be displayed.
3-25

Automatic Operation
AUTO (Automatic):When automatic operation is
active the system will control the inside temperature, the
air delivery, and the fan speed.
Use the steps below to place the entire system in
automatic mode:
1. Press the AUTO button.
When AUTO is selected, the display will change to
show the current driver’s set temperature, delivery
mode and fan speed. Press the AUTO button again
within ve seconds to display the passenger’s set
temperature.
If the driver and passenger’s temperature settings
are not the same, the opposite side temperature
setting will be displayed for an additional ve
seconds. To make the passenger’s temperature the
same as the driver’s press and hold the AUTO
button for about four seconds.
When AUTO is selected, the air conditioning
operation and air inlet will be automatically
controlled. The air conditioning compressor will run
when the outside temperature is over about
40°F (4°C). The air inlet will normally be set to
outside air. If it’s hot outside, the air inlet may
automatically switch to recirculate inside air to help
quickly cool down your vehicle. The light on the
button will illuminate in recirculation.2. Set the driver’s and passenger’s temperature.
To nd your comfort setting, start with a 74°F (23°C)
temperature setting and allow about 20 minutes
for the system to regulate. Turn the driver’s or
passenger’s side temperature knob to adjust the
temperature setting as necessary. If you choose the
temperature setting of 60°F (15°C) the system
will remain at the maximum cooling setting. If you
choose the temperature setting of 90°F (32°C)
the system will remain at the maximum heat setting.
Choosing either maximum setting will not cause
the vehicle to heat or cool any faster.
Be careful not to cover the sensor located on the
top of the instrument panel near the windshield.
This sensor regulates air temperature based on sun
load, and also turns on your headlamps.
To avoid blowing cold air in cold weather, the
system will delay turning on the fan until warm air is
available. The length of delay depends on the
engine coolant temperature. Pressing the fan switch
will override this delay and change the fan to a
selected speed.
3-26

The traction off light may come on for the following
reasons:
If you turn the system off by pressing the TAS on/off
button located to the left of the steering wheel, the
light will come on and stay on. To turn the system
back on, press the button again; the light should
go off.
If you move the shift lever to FIRST (1), the light will
come on and stay on to indicate that the traction
system is off. This is normal operation.
To turn the system back on, move the shift lever back
to a position other than FIRST (1); the light should go
off. SeeTraction Assist System (TAS) on page 4-8.
The light will come on and stay on if the TAS
automatic engagement feature has been turned off.
To turn the system on, press the TAS off/on button;
the light should go off. To turn the automatic
engagement feature back on, seeTraction Assist
System (TAS) on page 4-8.
If the Traction Assist System is affected by an
anti-lock brake system, TAS or engine-related
problem, the system will turn off and the light will
come on. Have your vehicle serviced.
If the vehicle is driven over an extremely rough road,
the system will turn off and the light will come on. The
light will go off a few seconds after the rough road
conditions go away or when the vehicle comes to a
complete stop. This is normal operation.
Engine Coolant Temperature Gage
This gage shows the engine coolant temperature.
It also provides an indicator of how hard your vehicle is
working. During a majority of the operation, the gage
will read 210°F (100°C) or less. If you are pulling a load
or going up hills, it is normal for the temperature to
uctuate and approach the 250°F (122°C) mark. If the
gage reaches the 260°F (125°C) mark, it indicates
that the cooling system is working beyond its capacity.
SeeEngine Overheating on page 5-37. United States
Canada
3-42

CHECK OIL LEVEL
If your vehicle is equipped with an oil level sensor, and
the oil level in the vehicle is low, this message will
appear on the DIC. Check the oil level and correct it as
necessary. You may need to let the vehicle cool or
warm up and cycle the ignition to be sure this message
will clear. Once the problem is corrected, pressing
any of the four DIC buttons, if equipped, will
acknowledge the message and clear it from the DIC
display. If your vehicle is not equipped with the four DIC
buttons, pressing the trip odometer reset stem will
acknowledge the message and clear it from the DIC
display. SeeEngine Oil (Gasoline Engine) on page 5-20
for additional information.
CHECK WASHER FLUID
If the washer uid level is low, this message will appear
on the DIC. SeeWindshield Washer Fluid on
page 5-48. Adding washer uid will clear the message.
Pressing any of the four DIC buttons, if equipped,
will acknowledge the message and clear it from the DIC
display. If your vehicle is not equipped with the
four DIC buttons, pressing the trip odometer reset stem
will acknowledge the message and clear it from the
DIC display.
DRIVER DOOR AJAR
If the driver’s door is not fully closed, this message will
appear on the display and you will hear a chime.
Stop and turn off the vehicle, check the door for
obstacles and close the door again. Check to see if the
message still appears on the DIC. Pressing any of
the four DIC buttons, if equipped, will acknowledge the
message and clear it from the DIC display. If your
vehicle is not equipped with the four DIC buttons,
pressing the trip odometer reset stem will acknowledge
the message and clear it from the DIC display.
ENGINE COOLANT HOT
If the cooling system temperature gets hot, this message
will appear in the DIC. Stop the vehicle and let the
engine idle in PARK (P), or FIRST (1) for manual
transmissions, to allow the coolant to reach a safe
temperature. This message will clear when the coolant
temperature drops to safe operating temperature.
3-56

ENGINE OVERHEATED
If the engine cooling system reaches unsafe
temperatures for operation, this message will appear in
the DIC and you will hear a chime. Stop and turn off
the vehicle as soon as it is safe to do so to avoid severe
damage. This message will clear when the engine
has cooled to a safe operating temperature.
Notice:If you drive your vehicle while the engine is
overheating, severe engine damage may occur.
If an overheat warning appears on the instrument
panel cluster and/or DIC, stop the vehicle as soon as
possible. Do not increase the engine speed above
normal idling speed. SeeEngine Overheating
on page 5-37for more information.
FUEL LEVEL LOW
If the fuel level is low, this message will appear on the
DIC and you will hear a chime. Refuel as soon as
possible. Pressing any of the four DIC buttons, if
equipped, will acknowledge the message and clear it
from the DIC display. If your vehicle is not equipped with
the four DIC buttons, pressing the trip odometer reset
stem will acknowledge the message and clear it from the
DIC display. SeeFuel Gage on page 3-49andFuel
on page 5-6.
KEYFOB X BATTERY LOW
If a remote keyless entry transmitter battery is low, this
message will appear on the DIC. The battery needs
to be replaced in the transmitter. See “Battery
Replacement” underRemote Keyless Entry System
Operation on page 2-5. Pressing any of the four
DIC buttons, if equipped, will acknowledge the message
and clear it from the DIC display. If your vehicle is
not equipped with the four DIC buttons, pressing the trip
odometer reset stem will acknowledge the message
and clear it from the DIC display.
LEFT REAR DOOR AJAR (Crew Cab)
If the driver’s side rear door is not fully closed, this
message will appear on the display and you will hear a
chime. Stop and turn off the vehicle, check the door
for obstacles and close the door again. Check to see if
the message still appears on the DIC. Pressing any
of the four DIC buttons, if equipped, will acknowledge
the message and clear it from the DIC display. If
your vehicle is not equipped with the four DIC buttons,
pressing the trip odometer reset stem will acknowledge
the message and clear it from the DIC display.
3-57

LOW COOLANT LEVEL
If your vehicle is equipped with a low coolant level sensor,
this message will appear on the DIC if the engine coolant
level is low. Adding coolant will clear the message. See
Cooling System on page 5-40. Pressing any of the
four DIC buttons, if equipped, will acknowledge the
message and clear it from the DIC display. If your vehicle
is not equipped with the four DIC buttons, pressing the
trip odometer reset stem will acknowledge the message
and clear it from the DIC display.
Notice:Engine damage from running your engine
without coolant is not covered by your warranty.
See “Overheated Engine Protection Operating
Mode” in the Index for information on driving to a
safe place in an emergency.
OIL LIFE RESET
This message will appear on the display for about
10 seconds after resetting the change engine oil
message. See “Engine Oil Life System” underDIC
Operation and Displays on page 3-51andEngine Oil
(Gasoline Engine) on page 5-20for more information.
OIL PRESSURE LOW
If low oil pressure levels occur, this message will be
displayed on the DIC and a chime will sound. Stop the
vehicle as soon as safely possible and do not operate
it until the cause of the low oil pressure has been
corrected. Check your oil as soon as possible and have
your vehicle serviced by your GM dealer. SeeEngine
Oil (Gasoline Engine) on page 5-20.
Notice:If you drive your vehicle while the engine
oil pressure is low, severe engine damage may
occur. If a low oil pressure warning appears on the
Driver Information Center (DIC), stop the vehicle
as soon as possible. Do not drive the vehicle until
the cause of the low oil pressure is corrected.
SeeEngine Oil (Gasoline Engine) on page 5-20for
more information.
PASSENGER DOOR AJAR
If the passenger’s door is not fully closed, this message
will appear on the display and you will hear a chime.
Stop and turn off the vehicle, check the door for
obstacles and close the door again. Check to see if the
message still appears on the DIC. Pressing any of
the four DIC buttons, if equipped, will acknowledge the
message and clear it from the DIC display. If your
vehicle is not equipped with the four DIC buttons,
pressing the trip odometer reset stem will acknowledge
the message and clear it from the DIC display.
3-58