2007 GMC SIERRA CLASSIC fuel

Service and Appearance Care
.................. 465
Service
................................................. 468
Fuel
...................................................... 470
Checking Things Under the Hood
......... 478
Rear Axle
............................................. 527
Four-Wheel Drive
.................................. 528
Front Axle
............................................ 529
Noise Control System
........................... 531
Bulb Replacement
................................ 532
Windshield Wiper Blade
Replacement
..................................... 542
Tires
..................................................... 543
Appearance Care
.................................. 589
Vehicle Identication
............................. 598
Electrical System
.................................. 599
Capacities and Specications
................ 609Maintenance Schedule
.............................. 613
Maintenance Schedule
.......................... 614
Customer Assistance Information
............. 637
Customer Assistance and
Information
........................................ 638
Reporting Safety Defects
...................... 656
Index
.......................................................... 659
2

Testing the Alarm
The alarm can be tested by following these steps:
1. From inside the vehicle, lower the driver’s
window and open the driver’s door.
2. Activate the system by locking the doors with
the RKE transmitter.
3. Get out of the vehicle, close the door and wait
for the security light to go out.
4. Then reach in through the window, unlock the
door with the manual door lock and open the
door. This should set off the alarm.
If the alarm does not sound when it should, but
the vehicle’s headlamps ash, check to see if the
horn works. The horn fuse may be blown. To
replace the fuse, seeFuses and Circuit Breakers
on page 600.
If the alarm does not sound or the vehicle’s
headlamps do not ash, see your dealer for
service.
Passlock®
Your vehicle has the Passlock®theft-deterrent
system.
Passlock
®is a passive theft-deterrent system.
Passlock®enables fuel if the ignition lock cylinder
is turned with a valid key. If a correct key is
not used or the ignition lock cylinder is tampered
with, fuel is disabled.
If the engine stalls and the security light ashes,
wait until the light stops ashing before trying
to restart the engine. Remember to release the key
from START as soon as the engine starts.
If the engine is running and the security light
comes on, you will be able to restart the engine if
you turn the engine off. However, your
Passlock
®system is not working properly and
must be serviced by your dealer. Your vehicle is
not protected by Passlock
®at this time. You
may also want to check the fuse. SeeFuses and
Circuit Breakers on page 600. See your dealer
for service.
In an emergency, call the GM Roadside
Assistance Center. SeeRoadside Assistance
Program on page 644.
133

When starting your engine in very cold weather
(below 0°F or−18°C), do this:
1. With your foot off the accelerator pedal, turn
the ignition key to START and hold it there up
to 15 seconds. When the engine starts, let
go of the key.
2. If your engine still will not start, or starts but
then stops, it could be ooded with too much
gasoline. Try pushing your accelerator pedal all
the way to the oor and holding it there as you
hold the key in START for about three seconds.
When the engine starts, let go of the key and
accelerator. If the vehicle starts briey but then
stops again, do the same thing, but this time
keep the pedal down for ve or six seconds.
This clears the extra gasoline from the engine.
Notice:Your engine is designed to work with
the electronics in your vehicle. If you add
electrical parts or accessories, you could
change the way the engine operates. Before
adding electrical equipment, check with your
dealer. If you do not, your engine might not
perform properly. Any resulting damage would
not be covered by your vehicle’s warranty.Engine Coolant Heater
In very cold weather, 0°F (−18°C) or colder, the
engine coolant heater can help. You will get easier
starting and better fuel economy during engine
warm-up. Usually, the coolant heater should
be plugged in a minimum of four hours prior to
starting your vehicle. At temperatures above
32°F (0°C), use of the coolant heater is not
required. Your vehicle may also have an internal
thermostat in the plug end of the cord. This
will prevent operation of the engine coolant
heater when the temperature is at or above
0°F (−18 C°) as noted on the cord.
To Use the Engine Coolant Heater
1. Turn off the engine.
2. Open the hood and unwrap the electrical
cord. The cord is located on the driver’s
side of the engine compartment, near
the power steering uid reservoir. If you have
a diesel engine, refer to diesel supplement
for location.
139

DRIVE (D):This position is for normal driving. It
provides the best fuel economy for your vehicle. If
you need more power for passing, and you are:
Going less than about 35 mph (55 km/h), push
your accelerator pedal about halfway down.
Going about 35 mph (55 km/h) or more, push
the accelerator all the way down.
By doing this, the vehicle shifts down to the
next gear and has more power.
Downshifting the transmission in slippery road
conditions could result in skidding, see “Skidding”
underLoss of Control on page 371
DRIVE (D) can be used when towing a trailer,
carrying a heavy load, driving on steep hills, or for
off-road driving. You may want to shift the
transmission to THIRD (3) or, if necessary, a lower
gear selection if the transmission shifts too often.
If your vehicle has the Allison Transmission
®, it will
shift into rst range when DRIVE (D) is selected.
As vehicle speed increases, the transmission
will upshift automatically through each available
range up to SIXTH (6). As the vehicle slows,
the transmission will downshift automatically.The Allison Transmission
®uses 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 will be able
to maintain vehicle speed by analyzing things
such as throttle position, vehicle load, and
hill grade. If the shift stabilization feature
determines that current vehicle speed cannot be
maintained, the transmission does not upshift
and instead holds the current gear. In some cases,
this may appear to be a delayed shift, however
the transmission is operating normally.
The Allison Transmission
®also uses adaptive shift
controls. Adaptive shift controls continually
compares key shift parameters to pre-programmed
ideal shift conditions. The Allison Transmission
®
constantly makes adjustments to improve vehicle
performance according to the way the vehicle is
being used, such as with a heavy load. During this
adaptive shift controls process, some shifts may
feel different as the transmission determines
optimum settings for a particular shift.
143

Shift Speeds
{CAUTION:
If you skip a gear when you downshift,
you could lose control of your vehicle.
You could injure yourself or others. Do
not shift down more than one gear at a
time when you downshift.
Do not allow the engine Revolutions Per Minute
(RPM) to overspeed and enter the tachometer red
lines. Engine overspeed occurs when downshifting,
or descending a grade, at too high a vehicle
speed. When going down steep grades, always
select a gear at least one position lower than you
would use on climbing a grade. This will allow
the vehicle’s engine to provide some braking and
help to slow the vehicle as it goes down the
grade. Monitor your vehicle speed, acceleration
and engine RPM while applying the brakes as you
go down the grade to ensure you have complete
control over the vehicle.If your engine speed drops below 600 rpm, or if
the engine is not running smoothly, you should
downshift to the next lower gear. When operating
on slippery surfaces, downshift at lower than
normal vehicle speeds to prevent the tires from
slipping.
In vehicles that have a bench seat, move the
tallest beverage containers to the right cupholder
to provide additional clearance for the shift
lever.
For vehicles that have a center console, the front
cup holder pulls out and turns 180° to provide
additional clearance between tall beverage
containers and the shift lever.
Up-Shift Light
If your vehicle has a
manual transmission,
you may have a shift
light. This light will show
you when to shift to the
next higher gear for best
fuel economy.
152

When this light comes on, you can shift to the next
higher gear if weather, road and traffic conditions
allow. For the best fuel economy, accelerate slowly
and shift when the light comes on.
While you accelerate, it is normal for the light to
go on and off if you quickly change the position of
the accelerator.
If your vehicle has four-wheel drive and has a
manual transmission, disregard the shift light when
the transfer case is in Four-Wheel Low.
Ignore the shift light when you downshift.
Four-Wheel Drive
If your vehicle has four-wheel drive, you can send
your 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.
While driving on clean dry pavement and during
tight turns, you may experience a vibration in
the steering system.
Front Axle Locking Feature
The front axle locks and unlocks automatically
when you shift the transfer case. Some delay for
the axle to lock or unlock is normal.
Manual Transfer Case
The transfer case shift lever is located on the oor
to the right of the driver. Use this lever to shift
into and out of four-wheel drive.
153

{CAUTION:
Shifting the transfer case to NEUTRAL
can cause your vehicle to roll even if the
transmission is in PARK (P), or if you
have a manual transmission, even if you
are in gear. You or someone else could be
seriously injured. Be sure to set the
parking brake before placing the transfer
case in NEUTRAL. SeeParking Brake on
page 169.
N (Neutral):Shift to this setting only when your
vehicle needs to be towed. SeeRecreational
Vehicle Towing on page 424orTowing Your
Vehicle on page 423.2H (Two-Wheel Drive High):This setting is used
for driving in most street and highway situations.
The front axle is not engaged in two-wheel
drive. This setting also provides the best fuel
economy.
4H (Four-Wheel Drive High):Use this setting
when you need extra traction, such as on snowy or
icy roads or in most off-road situations. This
setting also engages the front axle to help drive
your vehicle. This is the best setting to use
when plowing snow.
You can shift from 2H to 4H or 4H to 2H while the
vehicle is moving. The front axle will engage
faster if you take your foot off of the accelerator
for a couple of seconds after you shift. In
extremely cold weather, it may be necessary to
stop or slow the vehicle to shift into 4H.
155

When Using the Manual Transfer Case

Shifting should be made using quick motions.
Shifting slowly may make it more difficult to
shift.
You may notice that it is harder to shift when
the vehicle is cold. After the vehicle warms
up the shifting will return to normal.
While in 4H or 4L you may experience
reduced fuel economy.
Avoid driving in four-wheel drive on clean, dry
pavement. Doing this may cause the tires to
wear faster, and make your transfer case
harder to shift, and run noisier.
Shifting from 2H (Two-Wheel Drive High)
to 4H (Four-Wheel Drive High)

Shifts between 2H and 4H can be made at
any vehicle speed.
It is easiest to shift the transfer case when
maintaining a constant speed or during a slight
acceleration. If possible, avoid shifting while
slowing down, as it will make it harder to shift.
Shift the transfer case lever in one continuous
motion into either the 4H or 2H position.
In extremely cold weather, it may be necessary
to slow or stop the vehicle to shift into 4H until
your vehicle has warmed up.
While in 4H, your vehicle can be driven at any
posted legal speed limit.
156