towing GMC SONOMA 2004 Owner's Guide

4. Reapply the regular brakes. Then apply your
parking brake, and then shift into PARK (P), or
REVERSE (R) for a manual transmission.
5. If you have a four-wheel-drive vehicle with an
automatic transfer case, be sure the transfer case is
in a drive gear–not in NEUTRAL.
6. Release the regular brakes.
When You Are Ready to Leave After
Parking on a Hill
1. Apply your regular brakes and hold the pedal down
while you:
•start your engine,
•shift into a gear, and
•release the parking brake.
2. Let up on the brake pedal.
3. Drive slowly until the trailer is clear of the chocks.
4. Stop and have someone pick up and store the
chocks.
Maintenance When Trailer Towing
Your vehicle will need service more often when you’re
pulling a trailer. SeePart A: Scheduled Maintenance
Services on page 6-4for more on this. Things that are
especially important in trailer operation are automatic
transmission fluid (don’t overfill), engine oil, axle
lubricant, belt, cooling system and brake system. Each
of these is covered in this manual, and the Index
will help you find 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.
4-63

{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 ame 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.
Notice:If the air cleaner/lter is off, a backre can
cause a damaging engine re. And, dirt can
easily get into your engine, which will damage it.
Always have the air cleaner/lter in place when you
are driving.
Automatic Transmission Fluid
When to Check and Change the
Automatic Transmission Fluid
A good time to check your automatic transmission fluid
level is when the engine oil is changed.
Change both the fluid and filter every 15,000 miles
(25 000 km) if the vehicle is mainly driven under one or
more of these conditions:
•In heavy city traffic where the outside temperature
regularly reaches 90°F (32°C) or higher.
•In hilly or mountainous terrain.
•When doing frequent trailer towing.
•Uses such as found in taxi, police or delivery
service.
If you do not use your vehicle under any of these
conditions, change the fluid and filter every 50,000 miles
(83 000 km).
SeePart A: Scheduled Maintenance Services on
page 6-4.
5-19

If No Steam Is Coming From Your
Engine
If you get an engine overheat warning but see or hear
no steam, the problem may not be too serious.
Sometimes the engine can get a little too hot when you:
•Climb a long hill on a hot day.
•Stop after high-speed driving.
•Idle for long periods in traffic.
•Tow a trailer. See “Driving on Grades” under
Towing a Trailer on page 4-55.
If you get the overheat warning with no sign of steam,
try this for a minute or so:
1. In heavy traffic, let the engine idle in NEUTRAL
while stopped. If it is safe to do so, pull off the
road, shift to PARK (P) or NEUTRAL and let the
engine idle.
2. Turn on your heater to full hot at the highest fan
speed and open the window as necessary.If you no longer have the overheat warning, you can
drive. Just to be safe, drive slower for about 10 minutes.
If the warning doesn’t come back on, you can drive
normally.
If the warning continues, pull over, stop, and park your
vehicle right away.
If there’s still no sign of steam, idle the engine for three
minutes while you’re parked. Push down the accelerator
until the engine speed is about twice as fast as
normal idle speed for at least three minutes while you’re
parked. If you still have the warning,turn off the
engine and get everyone out of the vehicleuntil it
cools down.
You may decide not to lift the hood but to get service
help right away.
5-27

Engine Fan Noise
This vehicle has a clutched engine cooling fan. When
the clutch is engaged, the fan spins faster to provide
more air to cool the engine. In most everyday driving
conditions, the clutch is not engaged. This improves fuel
economy and reduces fan noise. Under heavy vehicle
loading, trailer towing and/or high outside temperatures,
the fan speed increases when the clutch engages.
So you may hear an increase in fan noise. This
is normal and should not be mistaken as the
transmission slipping or making extra shifts. It is merely
the cooling system functioning properly. The fan will
slow down when additional cooling is not required and
the clutch disengages.
You may also hear this fan noise when you start the
engine. It will go away as the fan clutch disengages.
Power Steering Fluid
The power steering reservoir is located near the front of
the engine compartment on the driver’s side of the
vehicle.
When to Check Power Steering Fluid
It is not necessary to regularly check power steering fluid
unless you suspect there is a leak in the system or
you hear an unusual noise. A fluid loss in this system
could indicate a problem. Have the system inspected
and repaired. SeeEngine Compartment Overview
on page 5-12for reservoir location.
5-35

Long Trip/Highway Denition
Follow this scheduled maintenanceonlyif none of the
conditions from the Short Trip/City Scheduled
Maintenance are true. Do not use this schedule if the
vehicle is used for trailer towing, driven in a dusty area
or used off paved roads. Use the Short Trip/City
schedule for these conditions
Driving a vehicle with a fully warmed engine under
highway conditions will cause engine oil to break down
slower.
Long Trip/Highway Intervals
Every 7,500 Miles (12 500 km):Engine Oil and Filter
Change (or every 12 months, whichever occurs
first). Chassis Lubrication (or 12 months, whichever
occurs first). Drive Axle Service. Tire Rotation.
Every 15,000 Miles (25 000 km):Engine Air Cleaner
Filter Inspection. Automatic Transmission Service
(severe conditions only).
Every 30,000 Miles (50 000 km):Fuel Filter
Replacement. Engine Air Cleaner Filter Replacement.
Every 50,000 Miles (83 000 km):Automatic
Transmission Service (normal conditions).Every 100,000 Miles (166 000 km):Spark Plug Wire
Inspection. Spark Plug Replacement. Positive
Crankcase Ventilation (PCV) Valve Inspection.
Every 150,000 Miles (240 000 km):Cooling System
Service (or every 60 months, whichever occurs
first). Engine Accessory Drive Belt Inspection.
These intervals only summarize maintenance services.
Be sure to follow the complete scheduled maintenance
on the following pages.
Short Trip/City Scheduled
Maintenance
The services shown in this schedule up to 100,000 miles
(166 000 km) should be repeated after 100,000 miles
(166 000 km) at the same intervals for the life of
this vehicle. The services shown at 150,000 miles
(240 000 km) should be repeated at the same interval
after 150,000 miles (240 000 km) for the life of this
vehicle.
SeePart B: Owner Checks and Services on page 6-25
andPart C: Periodic Maintenance Inspections on
page 6-30.
6-6

Footnotes
†The U.S. Environmental Protection Agency or the
California Air Resources Board has determined that the
failure to perform this maintenance item will not nullify
the emission warranty or limit recall liability prior to
the completion of the vehicle’s useful life. We, however,
urge that all recommended maintenance services be
performed at the indicated intervals and the
maintenance be recorded.
#Lubricate the front suspension, ball joints, steering
linkage, parking brake cable guides, propshaft splines,
universal joints, constant velocity joint and brake
pedal springs.
+A good time to check your brakes is during tire
rotation. See Brake System Inspection on page 6-31.
**Drive axle service. See Part D: Recommended
Fluids and Lubricants on page 6-32 for proper lubricant
to use:
•Check uid level and add uid as needed. If driving
in dusty areas or when towing a trailer, drain uid
and rell every 15,000 miles (25 000 km).
•If your vehicle has a locking differential, drain uid
and rell at rst engine oil change.
•More frequent lubrication may be required for
heavy-duty or off-road use.
3,000 Miles (5 000 km)
❑Change engine oil and filter (or every 3 months,
whichever occurs first).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occurs first).(See footnote #.)
❑Check rear/front axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
6,000 Miles (10 000 km)
❑Change engine oil and filter (or every 3 months,
whichever occurs first).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occurs first).(See footnote #.)
❑Check rear/front axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.(See Footnote **.)
❑Rotate tires. SeeTire Inspection and Rotation on
page 5-68for proper rotation pattern and additional
information.(See footnote +.)
6-7

9,000 Miles (15 000 km)
❑Change engine oil and filter (or every 3 months,
whichever occurs first).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occurs first).(See footnote #.)
❑Check rear/front axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
12,000 Miles (20 000 km)
❑Change engine oil and filter (or every 3 months,
whichever occurs first).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occurs first).(See footnote #.)
❑Check rear/front axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
❑Rotate tires. SeeTire Inspection and Rotation on
page 5-68for proper rotation pattern and additional
information.(See footnote +.)
15,000 Miles (25 000 km)
❑Change engine oil and filter (or every 3 months,
whichever occurs first).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occurs first).(See footnote #.)
❑Inspect engine air cleaner filter. If necessary, replace
the filter. If vehicle is driven in dusty/dirty conditions,
inspect filter at every engine oil change. See
Engine Air Cleaner/Filter on page 5-18for more
information.An Emission Control Service. (See
footnote †.)
❑Check rear/front axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
❑Change automatic transmission fluid and filter if the
vehicle is mainly driven under one or more of these
conditions:
- In heavy city traffic where the outside
temperature regularly reaches 90°F (32°C) or
higher.
- In hilly or mountainous terrain.
- When doing frequent trailer towing.
- Uses such as found in taxi, police or delivery
service.
If you do not use your vehicle under any of these
conditions, change the uid and lter every 50,000 miles
(83 000 km).
6-8

30,000 Miles (50 000 km)
❑Change engine oil and filter (or every 3 months,
whichever occurs first).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occurs first).(See footnote #.)
❑Check rear/front axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
❑Replace fuel filter.An Emission Control Service. (See
footnote †.)
❑Replace engine air cleaner filter. SeeEngine Air
Cleaner/Filter on page 5-18for more information.
An Emission Control Service.
❑Change automatic transmission fluid and filter if the
vehicle is mainly driven under one or more of these
conditions:
- In heavy city traffic where the outside
temperature regularly reaches 90°F (32°C) or
higher.
- In hilly or mountainous terrain.
- When doing frequent trailer towing.
- Uses such as found in taxi, police or delivery
service.If you do not use your vehicle under any of these
conditions, change the uid and lter every 50,000 miles
(83 000 km).
❑Rotate tires. SeeTire Inspection and Rotation on
page 5-68for proper rotation pattern and additional
information.(See footnote +.)
33,000 Miles (55 000 km)
❑Change engine oil and filter (or every 3 months,
whichever occurs first).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occurs first).(See footnote #.)
❑Check rear/front axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
36,000 Miles (60 000 km)
❑Change engine oil and filter (or every 3 months,
whichever occurs first).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occurs first).(See footnote #.)
❑Check rear/front axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
❑Rotate tires. SeeTire Inspection and Rotation on
page 5-68for proper rotation pattern and additional
information.(See footnote +.)
6-10

39,000 Miles (65 000 km)
❑Change engine oil and filter (or every 3 months,
whichever occurs first).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occurs first).(See footnote #.)
❑Check rear/front axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
42,000 Miles (70 000 km)
❑Change engine oil and filter (or every 3 months,
whichever occurs first).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occurs first).(See footnote #.)
❑Check rear/front axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
❑Rotate tires. SeeTire Inspection and Rotation on
page 5-68for proper rotation pattern and additional
information.(See footnote +.)
45,000 Miles (75 000 km)
❑Change engine oil and filter (or every 3 months,
whichever occurs first).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occurs first).(See footnote #.)❑Check rear/front axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
❑Change automatic transmission fluid and filter if the
vehicle is mainly driven under one or more of these
conditions:
- In heavy city traffic where the outside
temperature regularly reaches 90°F (32°C) or
higher.
- In hilly or mountainous terrain.
- When doing frequent trailer towing.
- Uses such as found in taxi, police or delivery
service.
If you do not use your vehicle under any of these
conditions, change the uid and lter every 50,000 miles
(83 000 km).
❑Inspect engine air cleaner filter. If necessary, replace
the filter. If vehicle is driven in dusty/dirty conditions,
inspect filter at every engine oil change. See
Engine Air Cleaner/Filter on page 5-18for more
information.An Emission Control Service. (See
footnote †.)
6-11

60,000 Miles (100 000 km)
❑Change engine oil and filter (or every 3 months,
whichever occurs first).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occurs first).(See footnote #.)
❑Check rear/front axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
❑Change automatic transmission fluid and filter if the
vehicle is mainly driven under one or more of these
conditions:
- In heavy city traffic where the outside
temperature regularly reaches 90°F (32°C) or
higher.
- In hilly or mountainous terrain.
- When doing frequent trailer towing.
- Uses such as found in taxi, police or delivery
service.
If you do not use your vehicle under any of these
conditions, change the uid and lter every 50,000 miles
(83 000 km).
❑Replace fuel filter.An Emission Control Service. (See
footnote †.)❑Replace engine air cleaner filter. SeeEngine Air
Cleaner/Filter on page 5-18for more information.
An Emission Control Service.
❑Rotate tires. SeeTire Inspection and Rotation on
page 5-68for proper rotation pattern and additional
information.(See footnote +.)
63,000 Miles (105 000 km)
❑Change engine oil and filter (or every 3 months,
whichever occurs first).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occurs first).(See footnote #.)
❑Check rear/front axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
66,000 Miles (110 000 km)
❑Change engine oil and filter (or every 3 months,
whichever occurs first).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occurs first).(See footnote #.)
❑Check rear/front axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
❑Rotate tires. SeeTire Inspection and Rotation on
page 5-68for proper rotation pattern and additional
information.(See footnote +.)
6-13