ECU GMC YUKON 2003 Workshop Manual

Four-Wheel-Drive Vehicles
Use the following procedure to tow your vehicle:
1. Firmly set the parking brake.
2. Shift the transmission to PARK (P).3. Securely attach the vehicle being towed to the tow
vehicle.
4. Shift the transfer case to NEUTRAL. See
Four-Wheel Drive on page 2-26for the proper
procedure to select the NEUTRAL position for your
vehicle.
5. Release the parking brake only after the vehicle
being towed isrmly attached to the following
vehicle.
6. Turn the ignition off.
{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 isfirmly set before you shift the
transfer case to NEUTRAL.
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Dolly Towing
Two-Wheel-Drive Vehicles
Two-wheel-drive, vehicles, should not be towed with the
rear wheels on the ground. Two-wheel-drive
transmissions have no provisions for internal lubrication
while being towed. to properly tow these vehicles,
they should be placed on a platform trailer with all four
wheels off the ground.
Four-Wheel-Drive Vehicles
If your vehicle is equipped with Stabilitrak®it is not
designed to be dolly towed. If you need to tow your
vehicle, see“Dinghy Towing”earlier in this section.
Use the following procedure to tow your vehicle:
1. Firmly set the parking brake.
2. Shift the transmission to PARK (P).
3. Securely attach the vehicle being towed to the tow
vehicle.4. Shift the transfer case to NEUTRAL. See
Four-Wheel Drive on page 2-26for the proper
procedure to select the NEUTRAL position for your
vehicle.
5. Release the parking brake only after the vehicle
being towed isrmly attached to the following
vehicle.
6. Turn the ignition off.{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 isfirmly set before you shift the
transfer case to NEUTRAL.
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2003 - Yukon/Yukon XL

Using heavier suspension components to get added
durability might not change your weight ratings. Ask your
dealer to help you load your vehicle the right way.
If you put things inside your vehicle–like suitcases,
tools, packages, or anything else–they go as fast
as the vehicle goes. If you have to stop or turn quickly,
or if there is a crash, they’ll keep going.
{CAUTION:
Things you put inside your vehicle can strike
and injure people in a sudden stop or turn, or
in a crash.
•Put things in the trunk of your vehicle. In a
trunk, put them as far forward as you can.
Try to spread the weight evenly.
•Never stack heavier things, like suitcases,
inside the vehicle so that some of them
are above the tops of the seats.
•Don’t leave an unsecured child restraint in
your vehicle.
•When you carry something inside the
vehicle, secure it whenever you can.There’s also important loading information for off-road
driving in this manual. See″Loading Your Vehicle
for Off-Road Driving″in the Index.
Level Control
Self-Adjusting
The self-adjusting rear suspension is available on
C/K 1500 vehicles and is available with the premium
smooth ride suspension package.
This type of level control will provide a leveled riding
position as well as improved handling under a variety of
passenger and loading conditions. A hydraulic pump
inside each rear shock absorber raises the rear of
the vehicle to the proper height, based on inputs from
the road surface, while the vehicle is being driven.
It takes approximately 2 miles (3.2 km) of driving for the
leveling to complete, depending on the road surface
conditions.
If the loaded vehicle is not moved for approximately
twelve hours, the leveling system may bleed down to a
lower height. This can be especially apparent if a trailer is
left attached to a parked vehicle for long periods of time.
The vehicle must be driven to re-level the vehicle.
If a self-equalizing hitch is being used, the vehicle
should be driven approximately 2 miles (3.2 km) with the
trailer prior to adjusting (leveling) the hitch.
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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.
Before you start, check the trailer hitch and platform
(and attachments), safety chains, electrical connector,
lamps, tires and mirror adjustment. If the trailer has
electric brakes, start your vehicle and trailer moving and
then apply the trailer brake controller by hand to be
sure the brakes are working. This lets you check your
electrical connection at the same time.
During your trip, check occasionally to be sure that the
load is secure, and that the lamps and any trailer
brakes are still working.
Following Distance
Stay at least twice as far behind the vehicle ahead as
you would when driving your vehicle without a trailer.
This can help you avoid situations that require
heavy braking and sudden turns.
Passing
You’ll need more passing distance up ahead when
you’re towing a trailer. And, because you’re a good deal
longer, you’ll need to go much farther beyond the
passed vehicle before you can return to your lane.
Backing Up
Hold the bottom of the steering wheel with one hand.
Then, to move the trailer to the left, just move that hand
to the left. To move the trailer to the right, move your
hand to the right. Always back up slowly and, if possible,
have someone guide you.
If your vehicle is equipped with four-wheel steering and
if you use it while backing your trailer the same rules
apply. However, with four-wheel steering your rig
will respond more quickly and it may take additional
practice to get used to backing up with four-wheel
steering.
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2003 - Yukon/Yukon XL

Ination -- Tire Pressure
The Certification/Tire label, which is on the rear edge of
the driver’s door, shows the correct inflation pressures
for your tires when they’re cold.“Cold”means your
vehicle has been sitting for at least three hours or driven
no more than 1 mile (1.6 km).
Notice:Don’t let anyone tell you that underination
or overination is all right. It’s not. If your tires
don’t have enough air (underination), you can get
the following:
Too muchexing
Too much heat
Tire overloading
Bad wear
Bad handling
Bad fuel economy
If your tires have too much air (overination), you
can get the following:
Unusual wear
Bad handling
Rough ride
Needless damage from road hazards
When to Check
Check your tires once a month or more.
Also, check the tire pressure of the spare tire.
How to Check
Use a good quality pocket-type gage to check tire
pressure. You can’t tell if your tires are properly inflated
simply by looking at them. Radial tires may look
properly inflated even when they’re underinflated.
Be sure to put the valve caps back on the valve stems.
They help prevent leaks by keeping out dirt and
moisture.
Tire Inspection and Rotation
Tires should be rotated every 7,500 miles (12 500 km).
Any time you notice unusual wear, rotate your tires
as soon as possible and check wheel alignment. Also
check for damaged tires or wheels. SeeWhen It Is Time
for New Tires on page 5-63andWheel Replacement
on page 5-66for more information.
Make sure the spare tire is stored securely. Push, pull,
and then try to rotate or turn the tire. If it moves,
use the ratchet/wheel wrench to tighten the cable. See
Changing a Flat Tire on page 5-69.
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Tire Chains
{CAUTION:
If your vehicle has P265/75R16, LT265/75R16,
P265/70R16 or P265/70R17 size tires, don’t use
tire chains. They can damage your vehicle
because there’s not enough clearance. Tire
chains used on a vehicle without the proper
amount of clearance can cause damage to the
brakes, suspension or other vehicle parts. The
area damaged by the tire chains could cause
you to lose control of your vehicle and you or
others may be injured in a crash.
Use another type of traction device only if its
manufacturer recommends it for use on your
vehicle and tire size combination and road
conditions. Follow that manufacturer’s
instructions. To help avoid damage to your
vehicle, drive slowly, readjust or remove the
device if it’s contacting your vehicle, and don’t
spin your wheels.
If you dond traction devices that willt,
install them on the rear tires.Notice:If you have a tire size other than P265/75R16,
LT265/75R16, P265/70R16 or P265/70R17 use tire
chains only where legal and only when you must. Use
chains that are the proper size for your tires. Install
them on the rear tires only.
Don’t use chains on the front tires.
Tighten them as tightly as possible with the ends
securely fastened. Drive slowly and follow the chain
manufacturer’s instructions. If you can hear the
chains contacting your vehicle, stop and retighten
them. If the contact continues, slow down until
it stops. Driving too fast or spinning the wheels with
chains on will damage your vehicle.
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2003 - Yukon/Yukon XL

4. Insert the hoist end (F)
through the hole (G) in
the rear bumper
and into the hoist
shaft.
5. Raise the tire part way upward. Make sure the
retainer is seated in the wheel opening.
6. Raise the tire fully against the underside of the
vehicle by turning the wheel wrench clockwise
until you hear two clicks or feel it skip twice. You
cannot overtighten the cable.A. Push and Pull
B. Rotate Tire
7. Make sure the tire is stored securely. Push, pull,
and then try to rotate or turn the tire. If the tire
moves, use the wheel wrench to tighten the cable.
Reinstall the spare tire lock (if equipped).
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2003 - Yukon/Yukon XL

To store the tools, follow these procedures:
For Tahoe/Yukon, do the following:
1. Put the tool kit, with the jack tools and gloves, in
the tool bag and place in the retaining clip above
the jack.
2. Tighten down with the wing nut.
3. Then, assemble wheel chocks and bottle jack
together with the wing nut and retaining hook.
4. Position behind the jack storage cover in the left
rear side panel and tighten, adjusting clockwise
until the jack is secured tight in the mounting
bracket. Be sure to position the holes in the base of
the jack onto the pin in the mounting bracket.
For Suburban/Yukon XLdo the following:
1. Return the tool kit (jack tools and gloves) to the
tool bag.
2. Assemble wheel chocks and bottle jack together
with the wing nut and retaining hook.
3. Position under the jack storage tray in the left rear
side panel below the wheelbase and tighten,
adjusting clockwise until the jack is secured tight in
the mounting bracket. Be sure to position the
holes in the base of the jack onto the pin in the
mounting bracket.4. Use the retaining clip to fasten the tool kit on the
stud in the storage compartment in the rear left
trim panel and turn the wing nut clockwise to
secure.
5. Return the storage tray.
A. Tool Kit with Jack
Tools and Gloves
B. Retaining Bracket
and Wing NutC. Wing Nut Holding
Tire Blocks
D. Tire Blocks
E. Bottle Jack Tahoe/Yukon (Rear Access Panel)
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7. Place the bottom edge of the jack on the wheel
blocks, separating them so that the jack is
balanced securely.
8. Attach the jack handle, extension, and wheel
wrench to the jack and place it (with the wheel
blocks) under the vehicle towards the front of the
rear bumper. Position the center lift point of the jack
under the center of the spare tire.
9. Turn the wrench clockwise to raise the jack until it
lifts the endfitting.
10. Continue raising the jack until the spare tire stops
moving upward and is heldfirmly in place. The
secondary latch has released and the spare tire is
balancing on the jack.
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At Least Twice a Year
Restraint System Check
Make sure the safety belt reminder light and all your
belts, buckles, latch plates, retractors and anchorages
are working properly. Look for any other loose or
damaged safety belt system parts. If you see anything
that might keep a safety belt system from doing its
job, have it repaired. Have any torn or frayed safety belts
replaced.
Also look for any opened or broken air bag coverings,
and have them repaired or replaced. (The air bag
system does not need regular maintenance.)
Wiper Blade Check
Inspect wiper blades for wear or cracking. Replace
blade inserts that appear worn or damaged or that
streak or miss areas of the windshield. Also see
Cleaning the Outside of Your Vehicle on page 5-92.
Spare Tire Check
At least twice a year, after the monthly ination check of
the spare tire determines that the spare is inated to
the correct tire ination pressure, make sure that
the spare tire is stored securely. Push, pull, and then try
to rotate or turn the tire. If it moves, use the wheel
wrench/ratchet to tighten the cable. SeeChanging a Flat
Tire on page 5-69.
Weatherstrip Lubrication
Silicone grease on weatherstrips will make them last
longer, seal better, and not stick or squeak. Apply
silicone grease with a clean cloth. During very cold,
damp weather more frequent application may be
required. SeePart D: Recommended Fluids and
Lubricants on page 6-17.
Automatic Transmission Check
Check the transmissionuid level; add if needed. See
Automatic Transmission Fluid on page 5-23.Auid loss
may indicate a problem. Check the system and repair
if needed.
At Least Once a Year
Key Lock Cylinders Service
Lubricate the key lock cylinders with the lubricant
specied in Part D.
Body Lubrication Service
Lubricate all hood latch assembly, secondary latch,
pivots, spring anchor, release pawl, rear compartment
hinges, outer liftgate handle pivot points, rear door
detent link, roller mechanism, liftgate handle pivot points,
latch bolt, fuel door hinge, cargo door hinge, locks
and folding seat hardware. Part D tells you what to use.
More frequent lubrication may be required when
exposed to a corrosive environment.
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