Electrical GMC SONOMA 2002 User Guide

4-57 Trailer Brakes
If your trailer weighs more than 1,000 lbs. (450 kg)
loaded, then it needs its own brakes
-- and they must be
adequate. Be sure to read and follow the instructions for
the trailer brakes so you'll be able to install, adjust and
maintain them properly.
Your trailer's brake system can tap into the vehicle's
hydraulic brake system only if:

The trailer parts can withstand 3,000 psi
(20 650 kPa) of pressure.

The trailer's brake system will use less than
0.02 cubic inch (0.3 cc) of fluid from your vehicle's
master cylinder. Otherwise, both braking systems
won't work well. You could even lose your brakes.
If everything checks out this far, then make the brake
fluid tap at the port on the master cylinder that sends
fluid to the rear brakes. But don't use copper tubing for
this. If you do, it will bend and finally break off. Use
steel brake tubing.
Driving with a Trailer
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.

5-4
2. Get the vehicles close enough so the jumper cables
can reach, but be sure the vehicles aren't touching
each other. If they are, it could cause a ground
connection you don't want. You wouldn't be able to
start your vehicle, and the bad grounding could
damage the electrical systems.
To avoid the possibility of the vehicles rolling, set the
parking brake firmly on both vehicles involved in the
jump start procedure. Put an automatic transmission in
PARK (P) or a manual transmission in NEUTRAL
before setting the parking brake. If you have a
four
-wheel-drive vehicle, be sure the transfer case is
not in NEUTRAL (N).
NOTICE:
If you leave your radio on, it could be badly
damaged. The repairs wouldn't be covered by
your warranty.
3. Turn off the ignition on both vehicles. Unplug
unnecessary accessories plugged into the cigarette
lighter or in the accessory power outlets. Turn off the
radio and all lamps that aren't needed. This will
avoid sparks and help save both batteries. And it
could save your radio!4. Open the hoods and locate the batteries. Find the
positive (+) and negative (
-) terminal locations on
each vehicle. See ªEngine Compartment Overviewº
in the Index for more information on location.
CAUTION:
Using a match near a battery can cause battery
gas to explode. People have been hurt doing this,
and some have been blinded. Use a flashlight if
you need more light.
Be sure the battery has enough water. You don't
need to add water to the ACDelco
battery
installed in every new GM vehicle. But if a
battery has filler caps, be sure the right amount
of fluid is there. If it is low, add water to take care
of that first. If you don't, explosive gas could be
present.
Battery fluid contains acid that can burn you.
Don't get it on you. If you accidentally get it in
your eyes or on your skin, flush the place with
water and get medical help immediately.

5-6
8. Now connect the black
negative (
-) cable to the
negative (
-) terminal of
the good battery. Use a
remote negative (
-)
terminal if the vehicle
has one.
Don't let the other end touch anything until the next
step. The other end of the negative (
-) cable doesn't
go to the dead battery. It goes to a heavy, unpainted
metal engine part, or to a remote negative (
-)
terminal on the vehicle with the dead battery.9. Connect the other end of the negative (
-) cable at
least 18 inches (45 cm) away from the dead battery,
but not near engine parts that move. The electrical
connection is just as good there, and the chance of
sparks getting back to the battery is much less.
10. Now start the vehicle with the good battery and run
the engine for awhile.
11. Try to start the vehicle that had the dead battery. If
it won't start after a few tries, it probably needs
service.
NOTICE:
Damage to your vehicle may result from
electrical shorting if jumper cables are removed
incorrectly. To prevent electrical shorting, take
care that they don't touch each other or any
other metal. The repairs wouldn't be covered by
your warranty.

6-
6-1
Section 6 Service and Appearance Care
Here you will find information about the care of your vehicle. This section begins with service and fuel information,
and then it shows how to check important fluid and lubricant levels. There is also technical information about your
vehicle, and a part devoted to its appearance care.
6
-2 Service
6
-3 Fuel (Gasoline)
6
-5 Fuel E-85 (85% Ethanol)
6
-7 Fuels in Foreign Countries
6
-7 Filling Your Tank
6
-9 Filling a Portable Fuel Container
6
-9 Checking Things Under the Hood
6
-13 Engine Oil
6
-18 Engine Air Cleaner/Filter
6
-19 Automatic Transmission Fluid
6
-23 Manual Transmission Fluid
6
-24 Hydraulic Clutch
6
-25 Rear Axle
6
-26 Four-Wheel Drive
6
-28 Engine Coolant
6
-31 Radiator Pressure Cap
6
-32 Power Steering Fluid6
-33 Windshield Washer Fluid
6
-34 Brakes
6
-38 Battery
6
-39 Bulb Replacement
6
-45 Windshield Wiper Blade Replacement
6
-47 Tires
6
-56 Appearance Care
6
-56 Cleaning the Inside of Your Vehicle
6
-59 Care of Safety Belts
6
-60 Cleaning the Outside of Your Vehicle
6
-64 GM Vehicle Care/Appearance Materials Chart
6
-65 Vehicle Identification Number (VIN)
6
-65 Service Parts Identification Label
6
-66 Electrical System
6
-72 Replacement Bulbs
6
-72 Capacities and Specifications
6
-74 Normal Maintenance Replacement Parts

6-39
Bulb Replacement
See ªReplacement Bulbsº in the Index for the proper
types of bulbs to use. For any bulb changing procedure
not listed in this section, contact your GM dealer's
service department.
Halogen Bulbs
CAUTION:
Halogen bulbs have pressurized gas inside and
can burst if you drop or scratch the bulb. You or
others could be injured. Be sure to read and
follow the instructions on the bulb package.
Headlamps
One-Piece Composite Headlamp System
1. Open the hood.
2. Remove the black retainer clips by lifting up.
3. Pull the headlamp assembly out.
4. Unplug the electrical connector.

6-40
5. Turn the bulb assembly counterclockwise to
remove it from the headlamp assembly.
6. Put the new bulb into the bulb assembly and
reinstall it in the headlamp assembly by turning it
clockwise until it is tight.
7. Plug in the electrical connector.
8. Put the headlamp assembly back into the vehicle.
9. Install the two retaining clips.
10. Close the hood.Tw o
-Piece Composite Headlamp System
1. Open the hood.
2. Remove the black retainer clips by lifting up.
3. Unplug the electrical connector.
4. Pull the headlamp lens assembly out.

6-41
5. Turn the bulb assembly counterclockwise to
remove it from the headlamp assembly.
6. Put the new bulb into the bulb assembly and
reinstall it in the headlamp assembly by turning it
clockwise until it is tight.
7. Plug in the electrical connector.
8. Put the headlamp lens assembly back into the
vehicle.
9. Install the two retaining clips.
10. Close the hood.
One-Piece Front Turn Signal Lamps
1. Remove the headlamp assembly as shown under
ªOne
-Piece Composite Headlamp Systemº earlier in
this section.
2. Twist the bulb socket
counterclockwise to
remove it from the
headlamp assembly.
3. Pull the bulb straight out to remove it from the
socket.
4. Push the new bulb into the socket until it snaps
into place.
5. Put the bulb socket into the lamp assembly and twist
it clockwise until it is tight.
6. Put the headlamp assembly back into the vehicle. I
7. Install the two retaining clips.
8. Close the hood.

6-42 Two-Piece Front Turn Signal Lamps
1. Remove the headlamp assembly as shown under
ªTwo
-Piece Composite Headlamp Systemº earlier in
this section.
2. Locate the locking tabs
on the assembly.
Squeeze the tabs
together and push that
end of the assembly out
while holding the tabs.
The assembly will
swing out.
3. Unplug the electrical connector.
4. Turn the harness bulb socket counterclockwise to
remove it. Pull the bulb straight out to remove it
from the socket.
5. Push the new bulb into the socket until it snaps
into place.
6. Put the socket into the lamp assembly and turn it
clockwise until it is tight.
7. To reinstall the assembly, snap the outboard end of
the lamp assembly back into the vehicle. Then swing
the assembly in and snap it into place.
8. Install the two retaining clips.
9. Close the hood.

6-66
Electrical System
Add-On Electrical Equipment
NOTICE:
Don't add anything electrical to your vehicle
unless you check with your dealer first. Some
electrical equipment can damage your vehicle
and the damage wouldn't be covered by your
warranty. Some add
-on electrical equipment
can keep other components from working as
they should.
Your vehicle has an air bag system. Before attempting to
add anything electrical to your vehicle, see ªServicing
Your Air Bag
-Equipped Vehicleº in the Index.
Headlamps
The headlamp wiring is protected by an internal
circuit breaker. An electrical overload will cause the
lamps to go on and off, or in some cases to remain off.
If this happens, have your headlamp wiring checked
right away.
Windshield Wipers
The windshield wiper motor is protected by a circuit
breaker and a fuse. If the motor overheats due to heavy
snow or ice the wiper will stop until the motor cools.
If the overload is caused by some electrical problem,
be sure to get it fixed.
Power Windows and Other Power Options
Circuit breakers protect the power windows and other
power accessories. When the current load is too heavy,
the circuit breaker opens and closes, protecting the
circuit until the problem is fixed or goes away.

6-67 Fuses and Circuit Breakers
The wiring circuits in your vehicle are protected from
short circuits by a combination of fuses and circuit
breakers. This greatly reduces the chance of fires caused
by electrical problems.
Look at the silver
-colored band inside the fuse. If the
band is broken or melted, replace the fuse. Be sure you
replace a bad fuse with a new one of the identical size
and rating.
If you ever have a problem on the road and don't have a
spare fuse, you can borrow one that has the same
amperage. Just pick some feature of your vehicle that
you can get along without
-- like the radio or cigarette
lighter
-- and use its fuse, if it is the correct amperage.
Replace it as soon as you can.
Instrument Panel Fuse Block
The instrument panel fuse
block is located at the end
of the instrument panel on
the driver's side.
Remove the cover by turning the fastener
counterclockwise. Extra fuses and the fuse extractor
are provided in the cover. To reinstall the fuse panel
cover, push in and turn the fastener clockwise.