1999 GMC SONOMA Switch

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If the 4HI switch is pressed when your vehicle is in gear
and/or moving, the 4HI indicator light will flash for
30 seconds but not complete the shift unless the vehicle
is moving slower than 3 mph (4.8 km/h) and the
transmission is in NEUTRAL (N) or the clutch
pedal engaged.
On automatic transmission equipped vehicles, if your
transfer case does not shift into 4HI, your transmission
indicator switch may require adjustment. With your
transmission in NEUTRAL (N), press and release the
4HI switch. While the 4HI indicator light is flashing,
shift your transmission into PARK (P). Wait until the
4HI indicator light remains illuminated before shifting
your transmission into gear. This will get you into 4HI,
but you should take your vehicle in for service to restore
normal operation.
Parking Brake
To set the parking brake, hold the regular brake pedal
down with your right foot. Push down the parking brake
pedal with your left foot. If the ignition is on, the brake
system warning light will come on.
To release the parking brake hold the regular brake
pedal down.
Pull the BRAKE RELEASE lever fully. It is located on
the bottom of the driver's side of the instrument panel.
NOTICE:
Driving with the parking brake on can cause
your rear brakes to overheat. You may have to
replace them, and you could also damage other
parts of your vehicle.
If you are towing a trailer and you must park on a hill,
see ªTowing a Trailerº in the Index. That section shows
what to do first to keep the trailer from moving.

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Engine Exhaust
CAUTION:
Engine exhaust can kill. It contains the gas
carbon monoxide (CO), which you can't see or
smell. It can cause unconsciousness and death.
You might have exhaust coming in if:

Your exhaust system sounds strange
or different.

Your vehicle gets rusty underneath.

Your vehicle was damaged in a collision.

Your vehicle was damaged when driving
over high points on the road or over
road debris.

Repairs weren't done correctly.

Your vehicle or exhaust system had been
modified improperly.
If you ever suspect exhaust is coming into
your vehicle:

Drive it only with all the windows down to
blow out any CO; and

Have your vehicle fixed immediately.
Running Your Engine While You're
Parked (Automatic Transmission)
It's better not to park with the engine running. But if
ever you have to, here are some things to know.
CAUTION:
Idling the engine with the climate control system
off could allow dangerous exhaust into your
vehicle (see the earlier Caution under
ªEngine Exhaustº).
Also, idling in a closed-in place can let deadly
carbon monoxide (CO) into your vehicle even if
the fan switch is at the highest setting. One place
this can happen is a garage. Exhaust
-- with
CO
-- can come in easily. NEVER park in a
garage with the engine running.
Another closed-in place can be a blizzard.
(See ªBlizzardº in the Index.)

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CAUTION:
It can be dangerous to get out of your vehicle if
the shift lever is not fully in PARK (P) with the
parking brake firmly set. Your vehicle can roll.
Don't leave your vehicle when the engine is
running unless you have to. If you've left the
engine running, the vehicle can move suddenly.
You or others could be injured. To be sure your
vehicle won't move, even when you're on fairly
level ground, always set your parking brake and
move the shift lever to PARK (P).
Follow the proper steps to be sure your vehicle won't
move. See ªShifting Into PARK (P)º in the Index.
If you're pulling a trailer, see ªTowing a Trailerº in
the Index.
Locking Rear Axle
If your vehicle has this feature, your locking rear axle
can give you additional traction on snow, mud, ice, sand
or gravel. It works like a standard axle most of the time,
but when one of the rear wheels has no traction and the
other does, this feature will allow the wheel with
traction to move the vehicle.
Windows
Manual Windows
Turn the hand crank on each door to raise or lower your
manual side door windows.
Power Windows (If Equipped)
If you have the optional power windows, the controls
are on each of the side doors. With power windows, the
switches control the windows when the ignition is on, in
ACCESSORY, or when Retained Accessory Power
(RAP) is present. (See ªRetained Accessory Powerº in
the Index.) The driver's door has a switch for the
passenger window as well.

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Press the side of the switch
with the down arrow to
lower the window.
Press the side of the switch with the up arrow to raise
the window.
Express
-Down Window
The driver's window switch also has an express
-down
feature that allows you to lower it without holding the
window switch. Hold the driver's window switch down
for more than a half a second to activate the
express
-down feature. Lightly tap the switch to open the
window slightly. The express
-down feature can be
interrupted at any time by pressing the up arrow end of
the switch.
Swing-Out Windows (Extended Cab)
To open a rear swing-out
window, pull the latch
toward the front of the
vehicle and then push the
latch out and rearward.
When you close the window, be sure the latch catches.

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Setting Cruise Control
CAUTION:
If you leave your cruise control switch on when
you're not using cruise, you might hit a button
and go into cruise when you don't want to. You
could be startled and even lose control. Keep the
cruise control switch off until you want to use
cruise control.
1. Move the cruise control switch to ON.
2. Get up to the speed you want.
3. Press in the SET button at the end of the lever and
release it.
4. Take your foot off the accelerator pedal.Resuming a Set Speed
Suppose you set your cruise control at a desired speed
and then you apply the brake. This, of course, shuts off
cruise control. But you don't need to reset it.
Once you're going about 25 mph (40 km/h) or more,
you can move the cruise control switch from ON to
R/A for about a half a second.
You'll go right back up to your chosen speed and
stay there.
If you hold the switch at R/A longer than a half a
second, the vehicle will keep going faster until you
release the switch or apply the brake. You could be
startled and even lose control. So unless you want to
go faster, don't hold the switch at R/A.

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Increasing Speed While Using Cruise Control
There are two ways to go to a higher speed:

Use the accelerator pedal to get to the higher speed.
Press the button at the end of the lever, then release
the button and the accelerator pedal. You'll now
cruise at the higher speed.

Move the cruise switch from ON to R/A. Hold it
there until you get up to the speed you want, and
then release the switch. To increase your speed in
very small amounts, move the switch to R/A.
Each time you do this, your vehicle will go about
1 mph (1.6 km/h) faster.
Reducing Speed While Using Cruise Control

Press in the button at the end of the lever until you
reach the lower speed you want, then release it.

To slow down in very small amounts, press the
button for less than a half a second. Each time you
do this, you'll go 1 mph (1.6 km/h) slower.
Passing Another Vehicle While Using Cruise Control
Use the accelerator pedal to increase your speed. When
you take your foot off the pedal, your vehicle will slow
down to the cruise control speed you set earlier.Using Cruise Control on Hills
How well your cruise control will work on hills depends
upon your speed, load and the steepness of the hills.
When going up steep hills, you may want to step on the
accelerator pedal to maintain your speed. When going
downhill, you may have to brake or shift to a lower gear
to keep your speed down. Of course, applying the brake
takes you out of cruise control. Many drivers find this
to be too much trouble and don't use cruise control
on steep hills.
Ending Cruise Control
There are two ways to turn off the cruise control:

Step lightly on the brake pedal or push the clutch
pedal, if you have a manual transmission.

Move the cruise switch to OFF.
Erasing Speed Memory
When you turn off the cruise control or the ignition,
your cruise control set speed memory is erased.

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Exterior Lamps
Your parking lamp and headlamp switch is on the
driver's side of your instrument panel.
Turn the knob clockwise to the parking lamps symbol to
manually turn on:

Parking Lamps

Sidemarker Lamps

Taillamps

License Plate Lamps

Instrument Panel LightsTurn the knob clockwise to the master lamps symbol to
turn on all the lamps listed as well as the headlamps.
Turn the knob all the way counterclockwise to turn off
your lamps and put the system in auto headlamp mode.
Automatic Headlamp System
When it is dark enough outside, your automatic
headlamp system will turn on your headlamps at the
normal brightness along with other lamps such as the
taillamps, sidemarker, parking lamps and the instrument
panel lights. The radio lights will also dim.
Your vehicle is equipped with a light sensor on the
top of the instrument panel under the radio speaker
grill. Be sure it is not covered or the system will be on
whenever the ignition is on.
The system may also turn on your headlamps when
driving through a parking garage, heavy overcast
weather, or a tunnel. This is normal.
There is a delay in the transition between the daytime
and nighttime operation of the Daytime Running Lamps
(DRL) and the automatic headlamp systems so that
driving under bridges or bright overhead street lights does
not affect the system. The DRL and automatic headlamp
system will only be affected when the light sensor sees a
change in lighting lasting longer than the delay.

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To idle your vehicle with the automatic headlamp
system off, set the parking brake while the ignition is
off. Then start your vehicle. The automatic headlamp
system will stay off until you release the parking brake.
As with any vehicle, you should turn on the regular
headlamp system when you need it.
Lamps On Reminder
A reminder chime will sound when your headlamps or
parking lamps are manually turned on and your ignition
is in OFF, LOCK or ACCESSORY. To turn the chime
off, turn the knob all the way to the left or turn the
instrument panel dimmer down to the fully dimmed
position. In the automatic mode, the headlamps turn
off once the ignition key is in OFF.
Daytime Running Lamps (If Equipped)
Daytime Running Lamps (DRL) can make it easier
for others to see the front of your vehicle during
the day. DRL can be helpful in many different driving
conditions, but they can be especially helpful in the
short periods after dawn and before sunset.
Fully functional daytime running lights are required on
all vehicles first sold in Canada.The DRL system will make your headlamps come on at
reduced brightness when:

the ignition is on,

the headlamp switch is in automatic headlamp mode,

the light sensor detects daytime light,

an automatic transmission is not in PARK (P), and

the parking brake is released.
When the DRL are on, only your headlamps will be on.
The taillamps, sidemarker and other lamps won't be on.
The instrument panel won't be lit up either.
When it begins to get dark, the headlamps will
automatically switch from DRL to the regular headlamps.
The DRL system on some vehicles may turn off
temporarily while the turn signals are activated.
To idle an automatic transmission vehicle with the
DRL off, put the transmission in PARK (P) or set the
parking brake. To idle a manual transmission vehicle
with the DRL off, set the parking brake. The DRL will
stay off until you shift out of PARK (P) or release the
parking brake.