1999 GMC YUKON ignition

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2-35
If you have to leave your vehicle with the engine
running, be sure your vehicle is in PARK (P) and the
parking brake is firmly set before you leave it. After you
move the shift lever into PARK (P), hold the regular
brake pedal down. Then, see if you can move the shift
lever away from PARK (P) without first pulling it
toward you. If you can, it means that the shift lever
wasn't fully locked into PARK (P).
Torque Lock
If you are parking on a hill and you don't shift your
transmission into PARK (P) properly, the weight of the
vehicle may put too much force on the parking pawl in
the transmission. You may find it difficult to pull the
shift lever out of PARK (P). This is called ªtorque lock.º
To prevent torque lock, set the parking brake and then
shift into PARK (P) properly before you leave the
driver's seat. To find out how, see ªShifting Into
PARK (P)º in the Index.
When you are ready to drive, move the shift lever out of
PARK (P) before you release the parking brake.
If torque lock does occur, you may need to have another
vehicle push yours a little uphill to take some of the
pressure from the parking pawl in the transmission, so
you can pull the shift lever out of PARK (P).
Shifting Out of PARK (P)
Your vehicle has a brake-transmission shift interlock
system. You have to fully apply your regular brakes
before you can shift from PARK (P) when the ignition is
in RUN. See ªAutomatic Transmissionº in the Index.
If you cannot shift out of PARK (P), ease pressure on
the shift lever and push the shift lever all the way up
into PARK (P) as you maintain brake application. Then,
move the shift lever into the gear you want.
If you ever hold the brake pedal down but still can't
shift out of PARK (P), try this:
1. Turn the key to the OFF ignition position.
2. Apply and hold the brake until the end of Step 4.
3. Shift the vehicle to NEUTRAL (N).
4. Start the vehicle and then shift to the drive gear
you want.
5. Have the brake
-transmission shift interlock system
fixed as soon as you can.

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Locking Rear Axle
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
Power Windows
The power window controls are located on each of the
side doors.The driver's door has a switch for the passenger
windows as well. Your power windows will work when
the ignition has been turned to ACCESSORY or RUN or
when Retained Accessory Power (RAP) is present. See
ªRetained Accessory Powerº in the Index.
Push the rear of the switch with the power window
symbol on it to lower the window.
Push the front of the switch with the power window
symbol on it to raise the window.
The driver's window switch has an express
-down
feature that allows the window to be lowered without
holding the switch. Press and hold the side of the
window switch marked AUTO for one second to
activate the express
-down mode. The express-down
mode can be canceled at any time by pressing the
opposite side of the switch. To open the window
partway, lightly tap the switch until the window is at the
desired position.
The power window switch has a lockout feature. This
feature prevents the passenger's windows from
operating except from the driver's position, when the
front driver's side switch is in LOCK. When the switch
is moved to NORM, the rear power windows will
operate again.

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Reducing Speed While Using Cruise Control
There are two ways to reduce your speed while using
cruise control:

Push in the SET 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, push the
button for less than 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 have to step on theaccelerator pedal to maintain your speed. If the
steepness of the hill causes the vehicle speed to drop
more than 15 mph (24 km/h) below the set speed, your
cruise control will automatically disengage. 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

Move the cruise control 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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2-47 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.
To idle your vehicle with the automatic headlamp
system off, set the parking brake while the ignition is
off. Then start the vehicle. The automatic headlamp
system will stay off until you release the parking brake.
The headlamp switch can always be used to turn on the
regular lamps. As with any vehicle, you should turn on
the regular headlamp system when you need it.
Headlamps-On Reminder
A chime will sound when your headlamps are turned on
and your ignition is in OFF, LOCK or ACCESSORY.
Daytime Running Lamps
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 DRL system will make your headlamps come on at
a reduced brightness when:

the ignition is on,

the headlamp switch is off,

the parking brake is released and

it is bright enough outside and the automatic
headlamps are off.
When the DRL are on, only your headlamps will be on.
The taillamps, sidemarker and other lamps won't be on.
Your instrument panel won't be lit up either.
When it begins to get dark, your DRL will turn off. Your
headlamps will come on automatically.
When it begins to get bright, the regular lamps will go
off, and your 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.

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2-48 Fog Lamps
Your vehicle has fog lamps. Use them for better vision
in foggy or misty conditions. Your parking lamps and/or
low
-beam headlamps must be on for your fog lamps
to work.
The fog lamp switch is
located to the right of the
instrument panel cluster.
Press the ribbed top part of the switch to turn the fog
lamps on. Press the bottom of the switch to turn them
off. An indicator light will illuminate in the switch when
the fog lamps are on.
Remember, fog lamps alone will not give off as much
light as your headlamps. Never use your fog lamps in
the dark without turning on your headlamps.Fog lamps will go off whenever your high
-beam
headlamps come on. When the high
-beams are off, the
fog lamps will come on again.
Headlamp Delay
Your vehicle is equipped with a headlamp delay feature
that holds the headlamps on for a short period of time
after the ignition is turned off.
The HEADLAMP DELAY button is located on the
lower left side of the inside rearview mirror.

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The length of time that the headlamps stay on after the
ignition is turned off can be adjusted by pressing and
holding the HEADLAMP DELAY button. The
delay can be varied in five steps (0, 15, 30, 60 and
90 seconds). When the HEADLAMP DELAY button is
held in, the Light Emitting Diode (LED) on the mirror
will show five step changes in brightness. When the
LED is at its brightest the headlamp delay will be
90 seconds, and when it is most dim the delay will be
zero seconds.
Interior Lamps
Instrument Panel Intensity Control
The instrument panel intensity control is located next to
the parking/headlamp switch. Turn the thumbwheel up
to adjust the instrument panel lights. Turn the
thumbwheel up to the first notch to return the radio
display and gear shift indicator LED display to full
intensity when the headlamps or parking lamps are on.
To turn on the dome lamps (with the vehicle doors
closed) turn the thumbwheel up to the second
notch position.
Exit Lighting and Delayed Illumination
With this feature, your interior lamps will come on and
stay on for up to 25 seconds when entering the vehicle
and up to 5 seconds when leaving your vehicle.
When the doors are opened, the dome lamps will only
come on if the dome lamp button is in the out position.
When all doors are closed or the dome lamp button is
pressed in, the lamps will stay on for a short period of
time and will then fade out.
Dome Lamps
The dome lamps will come on when you open the doors.
You can also turn the dome lamps on by turning the
thumbwheel, located next to the parking/headlamps
switch knob, all the way up to the second notch. In this
position, the dome lamps will remain on whether the
doors are opened or closed.

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You can use the DOME OVERRIDE button, located
below the parking/headlamp knob, to set the dome
lamps to come on automatically when the doors are
opened, or remain off. To turn the lamps off, press the
button once. With the button in this position, the dome
lamps will remain off when the doors are open. To
return the lamps to automatic operation, press the button
again and return it to the ªoutº position. With the button
in this position, the dome lamps will come on when you
open the door.
Reading Lamps
Your vehicle has reading
lamps. Press the button next
to the lamp to turn the
lamp on.
The lamps can be adjusted to point in the direction
you want.
Press the button again to turn the lamp off.
Battery Rundown Protection
This feature shuts off the dome, courtesy, vanity,
reading, glove box and underhood lamps if they are left
on for more than 20 minutes when the ignition is off.
This will keep your battery from running down.

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Temperature Display
The temperature can be displayed by pressing the TEMP
switch. Pressing the TEMP switch once briefly will
toggle the temperature reading on and off. To alternate
the temperature reading between Fahrenheit and Celsius,
press and hold the TEMP switch for three seconds until
the display shows only F
or C
. Press and release the
TEMP switch to toggle between the Fahrenheit and
Celsius readings. After five seconds of inactivity, the
display will return to normal in the temperature scale
you have selected.The normal display will show a temperature reading in
degrees Fahrenheit or Celsius. If an abnormal reading is
displayed, please consult your dealer.
Electrochromic Mirror Operation
The TEMP side of the switch, located at the bottom of
the mirror, also turns the electrochromic inside and
outside mirrors on and off. An indicator light, located to
the right of the TEMP switch, will come on when the
electrochromic mirrors are turned on. To turn the
mirrors on, press and hold the TEMP switch for eight
seconds. The mirrors will darken and remain dark until
the button is released. To turn the mirrors off, press and
hold the TEMP switch for eight seconds.
Compass Operation
Press the COMP switch once briefly to turn the compass
on or off.
When the ignition and the compass feature are on, the
compass will show two character boxes for
approximately two seconds. After two seconds, the
mirror will display the compass heading.