2007 GMC SIERRA CLASSIC cooling

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 obstructions, and close the door
again. Check to see if the message still appears
on the DIC. Pressing any of the four DIC
buttons will acknowledge the message and clear it
from the DIC display. If your vehicle does not
have the four DIC buttons, pressing the trip
odometer reset stem will acknowledge the
message and clear it from the DIC display.
RANGE SHIFT INHIBITED
(Allison Transmission®Only)
If the transmission is unable to shift into a selected
gear, this message will appear on the DIC. The
electronic shift position indicator on the instrument
panel cluster may blink when this occurs. To
make the vehicle shift to the requested gear, you
may have to shift back to PARK (P) or
NEUTRAL (N) and re-select the desired gear.
REDUCED ENGINE POWER
This message is displayed when the cooling
system temperature gets too hot and the engine
further enters the engine coolant protection mode.
SeeEngine Overheating on page 505for further
information.
This message will also display when the vehicle’s
engine power is reduced. Reduced engine
power can affect the vehicle’s ability to accelerate.
If this message is on, but there is no reduction
in performance, proceed to your destination. The
performance may be reduced the next time
the vehicle is driven. The vehicle may be driven at
a reduced speed while this message is on, but
acceleration and speed may be reduced. Anytime
this message stays on, the vehicle should be
taken to your dealer for service as soon as
possible.
276

After Off-Road Driving
Remove any brush or debris that has collected
on the underbody, chassis, or under the hood.
These accumulations can be a re hazard.
After operation in mud or sand, have the brake
linings cleaned and checked. These substances
can cause glazing and uneven braking. Check the
body structure, steering, suspension, wheels,
tires, and exhaust system for damage. Also, check
the fuel lines and cooling system for any leakage.
Your vehicle will require more frequent service
due to off-road use. Refer to the Maintenance
Schedule for additional information.
Driving at Night
Night driving is more dangerous than day driving.
One reason is that some drivers are likely to
be impaired — by alcohol or drugs, with night
vision problems, or by fatigue.
Here are some tips on night driving.
Drive defensively.
Do not drink and drive.
Adjust the inside rearview mirror to reduce the
glare from headlamps behind you.
Since you cannot see as well, you may need
to slow down and keep more space between
you and other vehicles.
Slow down, especially on higher speed roads.
Your vehicle’s headlamps can light up only so
much road ahead.
In remote areas, watch for animals.
If you are tired, pull off the road in a safe
place and rest.
No one can see as well at night as in the daytime.
But as we get older these differences increase.
A 50-year-old driver may require at least twice as
much light to see the same thing at night as a
20-year-old.
What you do in the daytime can also affect your
night vision. For example, if you spend the
day in bright sunshine you are wise to wear
sunglasses. Your eyes will have less trouble
adjusting to night. But if you are driving, do not
wear sunglasses at night. They may cut down on
glare from headlamps, but they also make a
lot of things invisible.
391

Hill and Mountain Roads
Driving on steep hills or mountains is different
from driving in at or rolling terrain.If you drive regularly in steep country, or if you are
planning to visit there, here are some tips that
can make your trips safer and more enjoyable.
SeeOff-Road Driving on page 372for information
about driving off-road.
Keep your vehicle in good shape. Check all
uid levels and also the brakes, tires, cooling
system, and transmission. These parts can
work hard on mountain roads.
{CAUTION:
If you do not shift down, your brakes
could get so hot that they would not work
well. You would then have poor braking or
even none going down a hill. You could
crash. Shift down to let your engine assist
your brakes on a steep downhill slope.
400

Driving with a Trailer
{CAUTION:
If you have a rear-most window open and
you pull a trailer with your vehicle, carbon
monoxide (CO) could come into your
vehicle. You cannot see or smell CO. It
can cause unconsciousness or death. See
Engine Exhaust on page 174. To maximize
your safety when towing a trailer:
Have your exhaust system inspected
for leaks, and make necessary repairs
before starting on your trip.
Keep the rear-most windows closed.
CAUTION: (Continued)
CAUTION: (Continued)

If exhaust does come into your vehicle
through a window in the rear or
another opening, drive with your front,
main heating or cooling system on
and with the fan on any speed. This
will bring fresh, outside air into your
vehicle. Do not use the climate control
setting for maximum air because it
only recirculates the air inside your
vehicle. SeeClimate Control System
on page 230.
Towing a trailer requires a certain amount of
experience. Before setting out for the open road,
you’ll want to get to know your rig. Acquaint
yourself with the feel of handling and braking with
the added weight of the trailer. And always
keep in mind that the vehicle you are driving is
now a good deal longer and not nearly as
responsive as your vehicle is by itself.
451

Maintenance When Trailer Towing
Your vehicle will need service more often when
you’re pulling a trailer. SeeScheduled
Maintenance (Gasoline Engine) on page 617for
more information. Things that are especially
important in trailer operation are automatic
transmission uid (don’t overll), engine oil, axle
lubricant, belt, cooling system and brake system.
Each of these is covered in this manual, and
the Index will help you nd them quickly. If you’re
trailering, it’s a good idea to review these
sections before you start your trip.
Check periodically to see that all hitch nuts and
bolts are tight.
Trailer Wiring Harness
Your vehicle is equipped with one of the following
wiring harnesses for towing a trailer or hauling
a slide-in camper.
Basic Trailer Wiring
All regular, extended cab and crew cab pickups
have an eight-wire trailer towing harness.For vehicles not equipped with heavy duty
trailering, the harness is clipped to the vehicle’s
frame behind the spare tire mount. The harness
requires the installation of a trailer connector,
which is available through your dealer.
If your trailer is equipped with electric brakes, you
can get a jumper harness (electric trailer brake
control) with a trailer battery feed fuse from
your dealer.
If you need to tow a light-duty trailer with a
standard four-way round pin connector, you can
also get an adapter from your dealer.
456

Service........................................................ 468
Accessories and Modications................... 468
California Proposition 65 Warning.............. 469
Doing Your Own Service Work.................. 469
Adding Equipment to the Outside of
Your Vehicle.......................................... 470
Fuel............................................................. 470
Gasoline Octane........................................ 470
Gasoline Specications.............................. 471
California Fuel........................................... 471
Additives................................................... 472
Fuel E85 (85% Ethanol)............................ 473
Fuels in Foreign Countries........................ 474
Filling the Tank......................................... 474
Filling a Portable Fuel Container............... 477
Checking Things Under the Hood.............. 478
Hood Release........................................... 479
Engine Compartment Overview.................. 480
Engine Oil (Gasoline Engine).................... 486
Engine Oil Life System
(Gasoline Engine).................................. 489
Engine Air Cleaner/Filter
(Gasoline Engines)................................. 491Automatic Transmission Fluid
(Allison Transmission®) .......................... 494
Automatic Transmission Fluid
(Except Allison Transmission
®) ............... 497
Manual Transmission Fluid........................ 500
Hydraulic Clutch........................................ 501
Engine Coolant.......................................... 502
Coolant Surge Tank Pressure Cap............ 505
Engine Overheating................................... 505
Overheated Engine Protection
Operating Mode (V8 Engines Only)........ 508
Cooling System......................................... 508
Engine Fan Noise..................................... 514
Power Steering Fluid ................................. 515
Windshield Washer Fluid........................... 516
Brakes...................................................... 517
Battery...................................................... 520
Jump Starting............................................ 521
Rear Axle.................................................... 527
Four-Wheel Drive........................................ 528
Front Axle................................................... 529
Section 5 Service and Appearance Care
465

A. Engine Air Cleaner/Filter. SeeEngine Air
Cleaner/Filter (Gasoline Engines) on page 491.
B. Coolant Surge Tank and Pressure Cap. See
Engine Coolant on page 502andCoolant
Surge Tank Pressure Cap on page 505.
C. Air Filter Restriction Indicator (If Equipped).
SeeEngine Air Cleaner/Filter (Gasoline
Engines) on page 491.
D. Engine Oil Dipstick. See “Checking Engine Oil”
underEngine Oil (Gasoline Engine) on
page 486.
E. Automatic Transmission Fluid Dipstick
(If Equipped). See “Checking the Fluid Level”
underAutomatic Transmission Fluid (Allison
Transmission
®) on page 494orAutomatic
Transmission Fluid (Except Allison
Transmission
®) on page 497.
F. Engine Cooling Fan. SeeCooling System on
page 508.G. Engine Oil Fill Cap. See “When to Add Engine
Oil” underEngine Oil (Gasoline Engine) on
page 486.
H. Power Steering Fluid Reservoir. SeePower
Steering Fluid on page 515.
I. Remote Negative (−) Terminal (GND). See
Jump Starting on page 521.
J. Remote Positive (+) Terminal. SeeJump
Starting on page 521.
K. Brake Fluid Reservoir. See “Brake Fluid” under
Brakes on page 517.
L. Clutch Fluid Reservoir (If Equipped). See
Hydraulic Clutch on page 501.
M. Underhood Fuse Block. SeeUnderhood Fuse
Block on page 603.
N. Battery. SeeBattery on page 520.
O. Windshield Washer Fluid Reservoir. See
“Adding Washer Fluid” underWindshield
Washer Fluid on page 516.
481

A. Engine Air Cleaner/Filter. SeeEngine Air
Cleaner/Filter (Gasoline Engines) on page 491.
B. Coolant Surge Tank and Pressure Cap. See
Engine Coolant on page 502andCoolant
Surge Tank Pressure Cap on page 505.
C. Air Filter Restriction Indicator (If Equipped).
SeeEngine Air Cleaner/Filter (Gasoline
Engines) on page 491.
D. Engine Oil Dipstick. See “Checking Engine Oil”
underEngine Oil (Gasoline Engine) on
page 486.
E. Automatic Transmission Fluid Dipstick
(If Equipped). See “Checking the Fluid Level”
underAutomatic Transmission Fluid (Allison
Transmission
®) on page 494orAutomatic
Transmission Fluid (Except Allison
Transmission
®) on page 497.
F. Engine Oil Fill Cap. See “When to Add Engine
Oil” underEngine Oil (Gasoline Engine) on
page 486.G. Engine Cooling Fan. SeeCooling System on
page 508.
H. Remote Negative (−) Terminal (GND). See
Jump Starting on page 521.
I. Power Steering Fluid Reservoir. SeePower
Steering Fluid on page 515.
J. Remote Positive (+) Terminal. SeeJump
Starting on page 521.
K. Brake Fluid Reservoir. See “Brake Fluid” under
Brakes on page 517.
L. Clutch Fluid Reservoir (If Equipped). See
Hydraulic Clutch on page 501.
M. Underhood Fuse Block. SeeUnderhood Fuse
Block on page 603.
N. Battery. SeeBattery on page 520.
O. Windshield Washer Fluid Reservoir. See
“Adding Washer Fluid” underWindshield
Washer Fluid on page 516.
483