transmission GMC SIERRA 2007 Workshop Manual

Four-Wheel-Drive Vehicles
Use the following procedure to tow your vehicle
from the rear:
1. Drive the vehicle onto the dolly.
2. Firmly set the parking brake. SeeParking
Brake on page 162.
3. Put the transmission in PARK (P).
4. Follow the dolly manufacturer’s instructions to
attach and secure the vehicle being towed to
the dolly and then the loaded dolly to the
tow vehicle.
Use an adequate clamping device to ensure
that the front wheels are locked into the
straight position.{CAUTION:
Shifting a four-wheel-drive vehicle’s
transfer case into NEUTRAL can cause
your vehicle to roll even if the
transmission is in PARK (P). You or
others could be injured. Make sure the
parking brake is rmly set before you shift
the transfer case to NEUTRAL.
5. Shift the transfer case to NEUTRAL. See
Four-Wheel Drive on page 147.
6. Release the parking brake only after the
vehicle being towed is rmly attached to
the tow vehicle.
7. Turn the ignition to LOCK.
444

If You Do Decide To Pull A Trailer
If you do, here are some important points:
There are many different laws, including speed
limit restrictions, having to do with trailering.
Make sure your rig will be legal, not only where
you live but also where you’ll be driving. A
good source for this information can be state
or provincial police.
Consider using a sway control. See “Hitches”
later in this section.
Don’t tow a trailer at all during the rst
500 miles (800 km) your new vehicle is driven.
Your engine, axle or other parts could be
damaged.
Then, during the rst 500 miles (800 km) that
you tow a trailer, don’t drive over 50 mph
(80 km/h) and don’t make starts at full throttle.
This helps your engine and other parts of your
vehicle wear in at the heavier loads.
You can tow in DRIVE (D). You may want to
shift the transmission to THIRD (3), or
FOURTH (4) with the Allison or Hydra-matic
6-speed transmissions, or if necessary, a lower
gear selection if the transmission shifts toooften, such as under heavy loads and/or hilly
conditions. SeeTow/Haul Mode Light on
page 266.
Three important considerations have to do with
weight:
The weight of the trailer
The weight of the trailer tongue
The weight on your vehicle’s tires
Tow/Haul Mode
Press this button at the end of the shift lever to
enable/disable the tow/haul mode.
446

Tow/Haul is a feature that assists when pulling a
heavy trailer or a large or heavy load. See
Tow/Haul Mode on page 144for more information.
Tow/Haul is designed to be most effective when
the vehicle and trailer combined weight is at
least 75 percent of the vehicle’s Gross Combined
Weight Rating (GCWR). See “Weight of the
Trailer” later in the section. Tow/Haul is most
useful under the following driving conditions:
When pulling a heavy trailer or a large
or heavy load through rolling terrain.
When pulling a heavy trailer or a large or
heavy load in stop and go traffic.
When pulling a heavy trailer or a large or
heavy load in busy parking lots where
improved low speed control of the vehicle is
desired.
Operating the vehicle in Tow/Haul when lightly
loaded or with no trailer at all will not cause
damage. However, there is no benet to the
selection of Tow/Haul when the vehicle is
unloaded. Such a selection when unloaded may
result in unpleasant engine and transmissiondriving characteristics and reduced fuel economy.
Tow/Haul is recommended only when pulling a
heavy trailer or a large or heavy load.
Weight of the Trailer
How heavy can a trailer safely be?
It depends on how you plan to use your rig. For
example, speed, altitude, road grades, outside
temperature and how much your vehicle is used to
pull a trailer are all important. It can also depend
on any special equipment that you have on
your vehicle, and the amount of tongue weight the
vehicle can carry. See “Weight of the Trailer
Tongue” later in this section for more information.
Maximum trailer weight is calculated assuming
only the driver is in the tow vehicle and it has all
the required trailering equipment. The weight
of additional optional equipment, passengers and
cargo in the tow vehicle must be subtracted
from the maximum trailer weight.
447

Turn Signals When Towing a Trailer
The arrows on your instrument panel will
ash whenever you signal a turn or lane change.
Properly hooked up, the trailer lamps will also
ash, telling other drivers you’re about to
turn, change lanes or stop.
When towing a trailer, the arrows on your
instrument panel will ash for turns even if the
bulbs on the trailer are burned out. Thus, you may
think drivers behind you are seeing your signal
when they are not. It’s important to check
occasionally to be sure the trailer bulbs are still
working.
Driving On Grades
Reduce speed and shift to a lower gearbefore
you start down a long or steep downgrade. If you
don’t shift down, you might have to use your
brakes so much that they would get hot and no
longer work well.You can tow in DRIVE (D). You may want to shift
the transmission to lower gear selection if the
transmission shifts too often (e.g., under heavy
loads and/or hilly conditions).
You may also want to activate the tow/haul mode
if the transmission shifts too often. SeeTow/Haul
Mode Light on page 266.
When towing at high elevation on steep uphill
grades, consider the following: Engine coolant at
higher elevations will boil at a lower temperature
than at or near sea level. If you turn your
engine off immediately after towing at high
elevation on steep uphill grades, your vehicle may
show signs similar to engine overheating. To
avoid this, let the engine run while parked,
preferably on level ground, with the transmission
in PARK (P) at least ve minutes before turning the
engine off. If you do get the overheat warning,
seeEngine Overheating on page 516.
475

Maintenance When Trailer Towing
Your vehicle will need service more often when
you’re pulling a trailer. SeeScheduled
Maintenance (Gasoline Engine) on page 623for
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 a seven-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 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.
478

Service........................................................ 486
Accessories and Modications................... 486
California Proposition 65 Warning.............. 487
Doing Your Own Service Work.................. 487
Adding Equipment to the Outside of
Your Vehicle.......................................... 488
Fuel............................................................. 488
Gasoline Octane........................................ 489
Gasoline Specications.............................. 489
California Fuel........................................... 489
Additives................................................... 490
Fuel E85 (85% Ethanol)............................ 491
Fuels in Foreign Countries........................ 492
Filling the Tank......................................... 493
Filling a Portable Fuel Container............... 495
Checking Things Under the Hood.............. 496
Hood Release........................................... 497
Engine Compartment Overview.................. 498
Engine Oil (Gasoline Engine).................... 500
Engine Oil Life System.............................. 503
Engine Air Cleaner/Filter
(Gasoline Engines)................................. 505Automatic Transmission Fluid.................... 508
Engine Coolant.......................................... 513
Coolant Surge Tank Pressure Cap............ 516
Engine Overheating................................... 516
Overheated Engine Protection Operating
Mode (V8 Engines Only)........................ 519
Cooling System......................................... 520
Engine Fan Noise..................................... 525
Power Steering Fluid................................. 526
Windshield Washer Fluid........................... 527
Brakes...................................................... 528
Battery...................................................... 531
Jump Starting............................................ 532
Rear Axle.................................................... 538
Four-Wheel Drive........................................ 539
Front Axle................................................... 541
Noise Control System................................. 542
Tampering with Noise Control System
Prohibited.............................................. 542
Section 5 Service and Appearance Care
483

A. Engine Air Cleaner/Filter. SeeEngine Air
Cleaner/Filter (Gasoline Engines) on page 505.
B. Air Filter Restriction Indicator (If Equipped).
SeeEngine Air Cleaner/Filter (Gasoline
Engines) on page 505.
C. Coolant Surge Tank and Pressure Cap. See
Cooling System on page 520andCoolant
Surge Tank Pressure Cap on page 516.
D. Positive (+) Terminal. SeeJump Starting on
page 532.
E. Battery. SeeBattery on page 531.
F. Engine Oil Fill Cap. See “When to Add Engine
Oil” underEngine Oil (Gasoline Engine) on
page 500.
G. Automatic Transmission Dipstick. See
“Checking the Fluid Level” underAutomatic
Transmission Fluid on page 508.H. Remote Negative (−) Terminal (Out of View).
SeeJump Starting on page 532.
I. Engine Oil Dipstick (Out of View). See
“Checking Engine Oil” underEngine Oil
(Gasoline Engine) on page 500.
J. Engine Cooling Fan. SeeCooling System on
page 520.
K. Power Steering Fluid Reservoir. SeePower
Steering Fluid on page 526.
L. Brake Master Cylinder Reservoir. See “Brake
Fluid” underBrakes on page 528.
M. Underhood Fuse Block. SeeUnderhood Fuse
Block on page 612.
N. Windshield Washer Fluid Reservoir. See
“Adding Washer Fluid” underWindshield
Washer Fluid on page 527.
499

5. Inspect or replace the engine air cleaner/lter.
6. Reinstall the cover and tighten the screws.
7. Reset the air lter restriction indicator, if
the vehicle has one, by pressing the top button
on the indicator.
{CAUTION:
Operating the engine with the air
cleaner/lter off can cause you or others
to be burned. The air cleaner not only
cleans the air; it helps to stop ames if
the engine backres. If it is not there and
the engine backres, you could be
burned. Do not drive with it off, and be
careful working on the engine with the air
cleaner/lter off.
Automatic Transmission Fluid
When to Check and Change Automatic
Transmission Fluid
It is usually not necessary to check the
transmission uid level. The only reason for uid
loss is a transmission leak or overheating the
transmission. If you suspect a small leak, then use
the following checking procedures to check the
uid level. However, if there is a large leak, then it
may be necessary to have the vehicle towed to
a dealership service department and have it
repaired before driving the vehicle further.
Notice:Use of the incorrect automatic
transmission uid may damage your vehicle,
and the damages may not be covered by
your warranty. Always use the automatic
transmission uid listed inRecommended
Fluids and Lubricants on page 635.
Change the uid and lter at the intervals listed in
the Maintenance Schedule. SeeScheduled
Maintenance (Gasoline Engine) on page 623.Be
sure to use the transmission uid listed in
Recommended Fluids and Lubricants on page 635.
508

How to Check Automatic Transmission
Fluid
Notice:Too much or too little uid can
damage your transmission. Too much can
mean that some of the uid could come out
and fall on hot engine parts or exhaust system
parts, starting a re. Too little uid could
cause the transmission to overheat. Be sure to
get an accurate reading if you check your
transmission uid.
Before checking the uid level, prepare your
vehicle as follows:
1. Start the engine and park your vehicle on a
level surface. Keep the engine running.
2. Apply the parking brake and place the shift
lever in PARK (P).3. With your foot on the brake pedal, move the
shift lever through each gear range, pausing
for about three seconds in each range.
Then, move the shift lever back to PARK (P).
4. Allow the engine to idle (500 – 800 rpm) for
at least one minute. Slowly release the brake
pedal.
5. Keep the engine running and press the
Trip/Fuel button or trip odometer reset
stem until TRANS TEMP (Transmission
Temperature) displays on the Driver
Information Center (DIC).
6. Using the TRANS TEMP reading, determine
and perform the appropriate check procedure.
If the TRANS TEMP reading is not within
the required temperature ranges, allow
the vehicle to cool, or operate the vehicle until
the appropriate transmission uid temperature
is reached.
509

Cold Check Procedure
Use this procedure only as a reference to
determine if the transmission has enough uid to
be operated safely until a hot check procedure
can be made. The hot check procedure is the most
accurate method to check the uid level. Perform
the hot check procedure at the rst opportunity.
Use this cold check procedure to check uid level
when the transmission temperature is between
80°F and 90°F (27°C and 32°C).
1. Locate the transmission dipstick at the rear of
the engine compartment, on the passenger’s
side of the vehicle.
The dipstick handle has
this graphic. SeeEngine
Compartment Overview
on page 498for
more information.
2. Flip the handle up, and then pull out the
dipstick and wipe it with a clean rag or
paper towel.3. Install the dipstick by pushing it back in all the
way, wait three seconds, and then pull it back
out again.
4. Check both sides of the dipstick, and read the
lower level. Repeat the check procedure to
verify the reading.
5. If the uid level is below the COLD check
band, add only enough uid as necessary
to bring the level into the COLD band. It does
not take much uid, generally less than
one pint (0.5L). Do not overll.
510