5. Drive the vehicle with the trailer attached on alevel road surface representative of the towing
condition and free of traffic at about 20 to 25 mph
(32 to 40 km/h) and fully apply the Manual Trailer
Brake Apply lever.
Adjusting trailer gain at speeds lower than
20 to 25 mph (32 to 40 km/h) may result in an
incorrect gain setting.
6. Adjust the Trailer Gain to just below the point of trailer wheel lock-up, indicated by trailer wheel
squeal or tire smoke when a trailer wheel locks.
Trailer wheel lock-up may not occur if towing a
heavily loaded trailer. In this case, adjust the
Trailer Gain to the highest allowable setting for
the towing condition.
7. Re-adjust Trailer Gain any time vehicle loading, trailer loading or road surface conditions change or
if trailer wheel lock-up is noticed at any time while
towingOther ITBC Related DIC Messages
In addition to displaying TRAILER GAIN and TRAILER
OUTPUT through the DIC, trailer connection and ITBC
system status is displayed in the DIC.
TRAILER CONNECTED –This message will be
briefly displayed when a trailer with electric brakes
is first connected to the vehicle. This message will
automatically turn off in about ten seconds. The driver
can also acknowledge this message before it
automatically turns off.
CHECK TRAILER WIRING –This message will be
displayed if:
1. The ITBC system first determines connection to a trailer with electric brakes and then the trailer
harness becomes disconnected from the vehicle.
If the disconnect occurs while the vehicle is
stationary, this message will automatically turn off
in about thirty seconds. This message will also turn
off if the driver acknowledges this message off or if
the trailer harness is re-connected.
If the disconnect occurs while the vehicle is
moving, this message will continue until the ignition
is turned off. This message will also turn off if the
driver acknowledges this message off or if the
trailer harness is re-connected.
5-62
To ensure quick starts in the wintertime, the E85 fuel
must be formulated properly for your climate according
to ASTM specification D 5798. If you have trouble
starting on E85, it could be because the E85 fuel is
not properly formulated for your climate. If this happens,
switching to gasoline or adding gasoline to the fuel tank
can improve starting. For good starting and heater
efficiency below 0°C (32°F), the fuel mix in the fuel tank
should contain no more than 70% ethanol. It is best
not to alternate repeatedly between gasoline and E85.
If you do switch fuels, it is recommended that you add
as much fuel as possible—do not add less than
11 L (3 gal) when refueling. You should drive the vehicle
immediately after refueling for at least 11 km (7 mi) to
allow the vehicle to adapt to the change in ethanol
concentration.
E85 has less energy per liter (gallon) than gasoline, so
you will need to refill the fuel tank more often when
using E85 than when you are using gasoline. See
Filling the Tank on page 6‑11. Notice:
Some additives are not compatible with E85
fuel and can harm the vehicle's fuel system. Do not
add anything to E85. Damage caused by additives
would not be covered by the vehicle warranty.
Notice: This vehicle was not designed for fuel that
contains methanol. Do not use fuel containing
methanol. It can corrode metal parts in the fuel
system and also damage plastic and rubber parts.
That damage would not be covered under the
vehicle warranty.
Fuels in Foreign Countries
If you plan on driving in another country outside the
United States or Canada, the proper fuel might be hard
to find. Never use leaded gasoline or any other fuel
not recommended in the previous text on fuel. Costly
repairs caused by use of improper fuel would not be
covered by the vehicle warranty.
To check the fuel availability, ask an auto club,
or contact a major oil company that does business
in the country where you will be driving.
6-10
Engine Oil Additives / Engine Oil
Flushes
Do not add anything to the oil. The recommended
oils with the starburst symbol that meet GM Standard
GM6094M are all that is needed for good performance
and engine protection.
Engine oil system flushes are not recommended and
could cause engine damage not covered by the vehicle
warranty.
Engine Oil Life System
When to Change Engine Oil
This vehicle has a computer system that indicates when
to change the engine oil and filter. This is based on
engine revolutions and engine temperature, and not on
mileage. Based on driving conditions, the mileage at
which an oil change is indicated can vary considerably.
For the oil life system to work properly, the system must
be reset every time the oil is changed.On some vehicles, when the system has calculated
that oil life has been diminished, a CHANGE ENGINE
OIL SOON message comes on to indicate that an oil
change is necessary. See
DIC Warnings and Messages
on page 4‑61. Change the oil as soon as possible
within the next 1 000 km (600 miles). It is possible that,
if driving under the best conditions, the oil life system
might not indicate that an oil change is necessary
for over a year. However, the engine oil and filter
must be changed at least once a year and at this time
the system must be reset. For vehicles without the
CHANGE ENGINE OIL SOON message, an oil change
is needed when the OIL LIFE REMAINING percentage
is near 0%. Your dealer has trained service people who
will perform this work using genuine parts and reset the
system. It is also important to check the oil regularly
and keep it at the proper level.
If the system is ever reset accidentally, the oil must
be changed at 5 000 km (3,000 miles) since the last
oil change. Remember to reset the oil life system
whenever the oil is changed.
6-20
How to Reset the Engine Oil Life
System
The Engine Oil Life System calculates when to
change the engine oil and filter based on vehicle use.
Whenever the oil is changed, reset the system so it
can calculate when the next oil change is required.
If a situation occurs where the oil is changed prior to
a CHANGE ENGINE OIL SOON message coming on,
reset the system.
Always reset the engine oil life to 100% after every oil
change. It will not reset itself. To reset the Engine Oil
Life System on most vehicles:1. Display the OIL LIFE REMAINING on the DIC. If the vehicle does not have DIC buttons, the
vehicle must be in P (Park) to access this display.
See DIC Operation and Displays (With DIC
Buttons)
on page 4‑48or DIC Operation and
Displays (Without DIC Buttons) on page 4‑55.
2. Press and hold the SET/RESET button on the DIC, or the trip odometer reset stem if the vehicle does
not have DIC buttons, for more than five seconds.
The oil life will change to 100%. On all vehicles, the Engine Oil Life System can be reset
as follows:
1. Turn the ignition to ON/RUN with the engine off
2. Fully press the accelerator pedal slowly three times within five seconds.
3. Display the OIL LIFE REMAINING on the DIC. If the display shows 100%, the system is reset.
See DIC Operation and Displays (With DIC
Buttons)
on page 4‑48or DIC Operation and
Displays (Without DIC Buttons) on page 4‑55.
If the vehicle has a CHANGE ENGINE OIL SOON
message and it comes back on when the vehicle is
started and/or the OIL LIFE REMAINING is near 0%,
the Engine Oil Life System has not reset. Repeat the
procedure.
6-21
Automatic Transmission Fluid
(4-Speed Transmission)
When to Check and Change Automatic
Transmission Fluid
A good time to check the automatic transmission fluid
level is when the engine oil is changed.
Change the fluid and filter at the intervals listed in
Scheduled Maintenance
on page 7‑3and be sure
to use the transmission fluid listed in Recommended
Fluids and Lubricants on page 7‑11.
How to Check Automatic Transmission
Fluid
Because this operation can be a little difficult, you
may choose to have this done at the dealer service
department.
If you do it yourself, be sure to follow all the instructions
here or you could get a false reading on the dipstick.
Notice: Too much or too little fluid can damage the
transmission. Too much can mean that some of the
fluid could come out and fall on hot engine parts or
exhaust system parts, starting a fire. Too little fluid
could cause the transmission to overheat. Be sure
to get an accurate reading if checking the
transmission fluid. Wait at least 30 minutes before checking the
transmission fluid level if you have been driving:
.When outside temperatures are above
32°C (90°F).
.At high speed for quite a while.
.In heavy traffic
—especially in hot weather.
.While pulling a trailer.
To get the right reading, the fluid should be at normal
operating temperature, which is 82°C to 93°C
(180°F to 200°F).
Get the vehicle warmed up by driving about
24 km (15 miles) when outside temperatures are above
10°C (50°F). If it is colder than 10°C (50°F), drive the
vehicle in 3 (Third) until the engine temperature gauge
moves and then remains steady for 10 minutes.
A cold fluid check can be made after the vehicle has
been sitting for eight hours or more with the engine off,
but this is used only as a reference. Let the engine
run at idle for five minutes if outside temperatures are
10°C (50°F) or more. If it is colder than 10°C (50°F),
you may have to idle the engine longer. Should the fluid
level be low during this cold check, you must check the
fluid hot before adding fluid. Checking the fluid hot will
give you a more accurate reading of the fluid level.
6-24
Reset the Tire Pressure Monitor System.
SeeTire Pressure Monitor Operation
on
page 6‑75
.
Make certain that all wheel nuts are properly
tightened. See “Wheel Nut Torque” under
Capacities and Specifications
on page 6‑126.
{WARNING:
Rust or dirt on a wheel, or on the parts to
which it is fastened, can make wheel nuts
become loose after time. The wheel could
come off and cause an accident. When you
change a wheel, remove any rust or dirt from
places where the wheel attaches to the
vehicle. In an emergency, you can use a
cloth or a paper towel to do this; but be
sure to use a scraper or wire brush later,
if needed, to get all the rust or dirt off.
See Changing a Flat Tire
on page 6‑88.
Make sure the spare tire is stored securely. Push,
pull, and then try to rotate or turn the tire. If it
moves, tighten the cable. See Storing a Flat or
Spare Tire and Tools
on page 6‑103.
When It Is Time for New Tires
Various factors, such as maintenance, temperatures,
driving speeds, vehicle loading, and road conditions,
influence when you need new tires.
One way to tell when it is
time for new tires is to
check the treadwear
indicators, which appear
when your tires have only
1/16 inch (1.6 mm) or less
of tread remaining. Some
commercial truck tires
may not have treadwear
indicators.
6-79
To clean:1. Saturate a lint-free, clean white cloth with water or club soda.
2. Wring the cloth to remove excess moisture.
3. Start on the outside edge of the soil and gently rub toward the center. Continue cleaning, using a clean
area of the cloth each time it becomes soiled.
4. Continue to gently rub the soiled area until the cleaning cloth remains clean.
5. If the soil is not completely removed, use a mild soap solution and repeat the cleaning process that
was used with plain water.
If any of the soil remains, a commercial fabric cleaner
or spot lifter may be necessary. When a commercial
upholstery cleaner or spot lifter is to be used, test a
small hidden area for colorfastness first. If the locally
cleaned area gives any impression that a ring formation
may result, clean the entire surface.
After the cleaning process has been completed, a paper
towel can be used to blot excess moisture from the
fabric or carpet.Leather
A soft cloth dampened with water can be used to
remove dust. If a more thorough cleaning is necessary,
a soft cloth dampened with a mild soap solution can
be used. Allow the leather to dry naturally. Do not use
heat to dry. Never use steam to clean leather. Never
use spot lifters or spot removers on leather. Many
commercial leather cleaners and coatings that are
sold to preserve and protect leather may permanently
change the appearance and feel of the leather and are
not recommended. Do not use silicone or wax-based
products, or those containing organic solvents to clean
the vehicle's interior because they can alter the
appearance by increasing the gloss in a non-uniform
manner. Never use shoe polish on leather.
6-110
When the Change Engine Oil Soon message displays,
certain services, checks, and inspections are required.
The services described for MaintenanceIshould be
performed at every engine oil change. The services
described for Maintenance IIshould be
performed when:
.Maintenance Iwas performed the last time the
engine oil was changed.
.It has been 10 months or more since the Change
Engine Oil Soon message has displayed or since
the last service.
Maintenance I
.Change engine oil and filter. See Engine Oilon
page 6‑18. An Emission Control Service.
.Engine coolant level check. See Engine Coolanton page 6‑32.
.Windshield washer fluid level check.
SeeWindshield Washer Fluid on page 6‑41.
.Tire inflation check. See Inflation - Tire Pressureon page 6‑72.
.Tire wear inspection. See Tire Inspection and
Rotation on page 6‑78.
.Rotate tires. See Tire Inspection and Rotationon
page 6‑78.
.Fluids visual leak check (or every 12 months,
whichever occurs first). A leak in any system must
be repaired and the fluid level checked.
.Engine air cleaner filter inspection (vehicles driven
in dusty conditions only). See Engine Air Cleaner/
Filter on page 6‑22.
.Brake system inspection (or every 12 months,
whichever occurs first).
Maintenance II
.Perform all services described in Maintenance I.
.Steering and suspension inspection. Visual
inspection for damaged, loose, or missing parts
or signs of wear.
.Lubricate the front suspension, steering linkage,
and parking brake cable guides. Control arm
ball joints on 2500 series vehicles require
lubrication but should not be lubricated unless
their temperature is−12°C (10°F) or higher, or
they could be damaged. Control arm ball joints
on 1500 series vehicles are maintenance‐free.
.Engine cooling system inspection. Visual
inspection of hoses, pipes, fittings, and clamps
and replacement, if needed.
7-4