GMC C-SERIES 1999 Manual Online

yellowblue
2-39
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
or clutch 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 different ways to turn off the cruise control:

Step lightly on the brake pedal.

Push the clutch pedal, if you have a
manual transmission.

Move the cruise switch to OFF.
Erasing Speed Memory
When you turn off the ignition, your cruise control set
speed memory is erased.Trailer Brake Hand Control Valve
(Option)
If your vehicle has this feature, it is mounted on the
steering column.
This control lets you apply the trailer brakes without
applying the tractor brakes. You can apply the trailer
brakes a little or apply them all the way if you have to.
Use this control only when you're driving. Don't use it
for parking or to hold the rig on a hill.
ProCarManuals.com

yellowblue
2-40
CAUTION:
Using the trailer brake hand control for parking
or for holding the vehicle on a hill may not keep
the vehicle from rolling. This can happen if
someone hits the valve by accident, or if air
pressure bleeds from the system. If the vehicle
rolls, you or others could be injured. To park the
vehicle or hold it on a hill, use the parking
brake properly.
Inter-Axle Differential Lock Control
(If Equipped)
If your vehicle has this
feature, the control is
located at the lower
right corner of the
instrument panel.
If you're approaching a slippery surface where it looks
like one or even all of the wheels may start to slip, you
can use this control. It locks your rear differentials so
that power is transmitted equally to both rear axles.
ProCarManuals.com

yellowblue
2-41
Let up on the accelerator before you turn on your
inter
-axle differential lock. When you turn on this
control, the DIFF LOCK indicator on the instrument
panel will light.
NOTICE:
Activating the inter-axle differential lock when
the rear wheels are actually spinning freely, as
they might on ice or snow, can cause you to lose
control of the vehicle. It can also damage the
axles. Turn on this control only when the wheels
are not spinning freely.
Rear Axle Differential Lock Control
(If Equipped)
If your vehicle has a
Controlled Traction or
Locking Differential axle,
the control is located at the
lower right corner of the
instrument panel. You'll see
this control on single rear
axle vehicles.
If you're approaching a slippery surface where it looks
like one or even both wheels may start to slip, you can
use this control. It locks your rear differential so that
power is transmitted equally to both rear wheels.
ProCarManuals.com

yellowblue
2-42
Let up on the accelerator before you turn on your rear
axle differential lock.
NOTICE:
Activating the rear-axle differential lock when
the rear wheels are actually spinning freely, as
they might on ice or snow, can cause you to lose
control of the vehicle. It can also damage the axle.
Turn on this control only when the wheels are not
spinning freely.
Engine Air Control (If Equipped)
If your vehicle has this control, the handle is located on
the instrument panel just to the right of the steering
wheel. The control is activated by pulling the handle out
and turning slightly in either direction to lock it.
ProCarManuals.com

yellowblue
2-43
When the handle is pulled out, the engine air intake
supply is closed off from the front scoop and an under
hood air supply is opened. This control is intended only
for use in cold weather (32
F (0
C) or below) where
snow and ice might plug the external intake.
At temperatures above 32
F (0
C), keep the control
handle pushed in.
NOTICE:
Operating this vehicle with the engine air control
on when outside temperatures are above 32
F
(0
C), could lead to costly repairs not covered by
your warranty. It will also degrade fuel economy
and the engine will not run smoothly.
Exterior Lamps
Headlamps
The lamp switches are on the left side of your
instrument panel.
ProCarManuals.com

yellowblue
2-44
Press the top left switch to turn on your:

Parking Lamps

Marker Lamps (unless your vehicle has the optional
marker and clearance lamps switch)

Taillamps

Instrument Panel Lights

License Plate Lamps
Push the bottom left switch to turn on the headlamps, as
well as all of the lamps just listed. Push the switch
marked with the ªOº symbol to turn off your lamps.
Move the thumbwheel to the right of the off switch
down to dim your instrument panel lights. Moving this
wheel up makes these lights brighter. Moving it all the
way up will make the interior lamp come on.
A circuit breaker protects your headlamps. If you have
an electrical overload, your headlamps will flicker on
and off. Have your headlamp wiring checked right away
if this ever happens.Headlamps On Reminder (If Equipped)
If you have this system, a tone alarm will sound when
your headlamps and/or parking lamps are turned on and
your ignition is in OFF, LOCK or ACCESSORY.
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.
The high and low
-beam headlamps will come on at
reduced brightness in daylight when:

The ignition is on,

The headlamp switch is off and

The parking brake is released.
When the DRL are on, only your low
-beam headlamps
will be on. The exterior lamps won't be on. Your
instrument panel won't be lit up either.
When it begins to get dark, your DRL indicator light is a
reminder to turn your headlamp switch on. The other
lamps that come on with your headlamps will also
come on.
ProCarManuals.com

yellowblue
2-45
When you turn the headlamp switch off, the regular
lamps will go off, and your low
-beam headlamps will
change to the reduced brightness of DRL.
To idle your vehicle with the DRL off, set the parking
brake. The DRL 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.
Marker and Clearance Lamps Switch
(If Equipped)
Your vehicle will have this
switch only if it is designed
to pull a trailer. If it has this
switch, you'll find it on the
upper right side of your
instrument panel, just above
the radio.If your vehicle has no radio, the switch is just above the
storage area. Use the switch to operate your clearance
and marker lamps. The marker lamps are illuminated
when the indicator light is on.
Your headlamps switch will not operate these lamps.
You can use the switch to manually blink the marker and
clearance lamps by simply turning it on and off.
ProCarManuals.com

yellowblue
2-46
Interior Lamps
Dome Lamp
The dome lamps will come on when you open the
driver's door. You can also turn the dome lamps on by
turning the interior lamp dimmer dial all the way up
until it clicks.
Mirrors
Inside Rearview Mirror (If Equipped)
Press the tab under the mirror to reduce glare at night
from headlamps behind you.
Outside Mirrors
Adjust the outside mirror or
mirrors by hand so you can
just see the side of your
vehicle when you're sitting
in the driver's seat. These
mirrors can fold in toward
the vehicle for entering
narrow garages and for
clearance in an automatic
vehicle wash.
If your mirrors have the clearance lamps, they'll be on
when your parking lamps are on.
Convex Outside Mirrors (Option)
Your vehicle may have optional convex mirrors. A
convex mirror's surface is curved so you can see more
from the driver's seat.
CAUTION:
A convex mirror can make things (like other
vehicles) look farther away than they really are.
If you cut too sharply into the right or left lane,
you could hit a vehicle. Check your regular
outside mirrors (or your inside mirror, if you
have one) before changing lanes.
ProCarManuals.com

yellowblue
2-47 Heated Outside Mirrors (If Equipped)
If your vehicle has heated
mirrors, you'll find this
switch on the upper right
side of your instrument
panel area, just above the
radio. Use it to operate your
mirror heaters to defrost or
defog your mirrors.
When you turn on the mirror heaters, an indicator light
in the switch will be lit to tell you the heaters are on.
Once the mirrors are clear for viewing, turn the switch
off. The mirror heaters remain on until the heater switch
or ignition switch is turned off. However, when you turn
the ignition back on, the heater switch will again be on
until turned off.
Ashtray and Cigarette Lighter
(If Equipped)
The ashtray is just below the gages on the right side of
your instrument panel. If you have a cigarette lighter, it
is inside the ashtray.
To use the lighter, press it in all the way and let go.
When it's ready, it will pop back by itself.
NOTICE:
Don't hold a cigarette lighter in with your hand
while it is heating. If you do, it won't be able to
back away from the heating element when it's
ready. That can make it overheat, damaging the
lighter and heating element.
To remove the ashtray for cleaning, pull up on the
front of it.
ProCarManuals.com

yellowblue
2-48
NOTICE:
Don't put papers and other things that burn into
your ashtray. If you do, cigarettes or other
smoking materials could set them on fire,
causing damage.
Sun Visors
To block out glare, you can move the sun visors. You
can also swing them from side to side.
Auxiliary Power Jacks (If Equipped)
If your vehicle has these
power jacks, you'll find
them in the ashtray.These jacks provide 12
-volt power so you can operate
things such as a citizen's band (CB) radio or a cellular
phone. You'll see positive (red) and negative (black)
outlets. They have a 20
-amp fuse that is common with
the cigarette lighter. Don't use the cigarette lighter when
you're using a power jack because it may overload the
circuit and blow the fuse.
NOTICE:
Whether or not your vehicle has the power
outlets, don't plug in FM communications gear at
the ashtray area. FM equipment creates high
heat, and over time the area could get so hot that
wires could be damaged or a fire could even
break out.
ProCarManuals.com