2000 GMC YUKON battery

3-33
5. Press AM-FM after you have confirmed that the
code matches the secret code you have written down.
The display will show SEC, indicating the radio is
now operable and secure.
If you enter the wrong code eight times, INOP will
appear on the display. You will have to wait an hour
with the ignition on before you can try again. When you
try again, you will only have three chances to enter the
correct code before INOP appears.
If you lose or forget your code, contact your dealer.
Disabling the Theft
-Deterrent Feature
Enter your secret code as follows; pause no more than
15 seconds between steps:
1. Turn the ignition to ACCESSORY or RUN.
2. Turn the radio off.
3. Press the 1 and 4 buttons together. Hold them down
until SEC shows on the display.4. Press MN and 000 will appear on the display.
5. Press MN again to make the last two digits agree
with your code.
Press HR to make the first one or two digits agree with
your code.
6. Press AM
-FM after you have confirmed that the
code matches the secret code you have written down.
The display will show
---, indicating that the radio
is no longer secured.
If the code entered is incorrect, SEC will appear on the
display. The radio will remain secured until the correct
code is entered.
When battery power is removed and later applied to a
secured radio, the radio won't turn on and LOC will
appear on the display.
To unlock a secured radio, see ªUnlocking the
Theft
-Deterrent Feature After a Power Lossº earlier
in this section.

4-43
CAUTION:
Snow can trap exhaust gases under your vehicle.
This can cause deadly CO (carbon monoxide) gas
to get inside. CO could overcome you and kill
you. You can't see it or smell it, so you might not
know it is in your vehicle. Clear away snow from
around the base of your vehicle, especially any
that is blocking your exhaust pipe. And check
around again from time to time to be sure snow
doesn't collect there.
Open a window just a little on the side of the
vehicle that's away from the wind. This will help
keep CO out.
Run your engine only as long as you must. This saves
fuel. When you run the engine, make it go a little faster
than just idle. That is, push the accelerator slightly.
This uses less fuel for the heat that you get and it
keeps the battery charged. You will need a well
-charged
battery to restart the vehicle, and possibly for signaling
later on with your headlamps. Let the heater run
for a while.
Then, shut the engine off and close the window almost
all the way to preserve the heat. Start the engine again
and repeat this only when you feel really uncomfortable
from the cold. But do it as little as possible. Preserve the
fuel as long as you can. To help keep warm, you can get
out of the vehicle and do some fairly vigorous exercises
every half hour or so until help comes.

4-44
Recreational Vehicle Towing
There may be times when you want to tow your vehicle
behind another vehicle for use at your destination.
Be sure to use the proper towing equipment designed
for recreational vehicle towing. Follow the instructions
for the towing equipment.
When towing your vehicle, turn the ignition to OFF.
To prevent your battery from draining while towing,
remove the IGN 0 fuse from the instrument panel fuse
block. Be sure to replace the fuse when you reach your
destination. See ªFuses and Circuit Breakersº in
the Index.
Two-Wheel-Drive Vehicles
Tw o-wheel-drive vehicles, should not be towed
with all four wheels on the ground. Two
-wheel-drive
transmissions have no provisions for internal lubrication
while being towed. To properly tow these vehicles, they
should be placed on a platform trailer with all four
wheels off the ground.
In rare cases when it's unavoidable that a
two
-wheel-drive vehicle is to be towed with all four
wheels on the ground, the propeller shaft to axle yoke
orientation should be marked and the propeller shaft
removed following the applicable service manual
removal/installation procedure.
Dust or dirt can enter the back of the transmission
through the opening created by removing the propeller
shaft if proper protection is not provided. Also, check
the transmission fluid level before driving the truck.

4-45 Four-Wheel-Drive Vehicles
CAUTION:
Shifting the transfer case into NEUTRAL (N) can
cause your vehicle to roll even if the transmission
is in PARK (P), for an automatic transmission.
You or others could be injured. Make sure the
parking brake is firmly set before you shift the
transfer case into NEUTRAL (N).

Firmly set the parking brake.

Shift the transmission to PARK (P).
Securely attach the vehicle being towed to
the tow vehicle.

Shift the transfer case to NEUTRAL (N).
See ªFour
-Wheel Driveº in the Index for
the proper procedure to select the NEUTRAL
position for your vehicle.

Release the parking brake only after the
vehicle being towed is firmly attached to the
towing vehicle.

Turn the ignition to OFF. The OFF position
unlocks the steering column and reduces battery
drain as long as the IGN 0 fuse is removed.
Unlocking the steering column will allow the
proper movement of the front wheels and tires
during towing.

4-63
The seven-wire harness contains the following
trailer circuits:

Yellow: Left Stop/Turn Signal

Dark Green: Right Stop/Turn Signal

Brown: Taillamps

White: Ground

Light Green: Back
-up Lamps

Red: Battery Feed

Dark Blue: Trailer Brake
If you need to upgrade your vehicle to heavy
-duty
trailering, a brake controller harness is available from
your dealer.Heavy
-Duty Trailer Wiring Package (If Equipped)
Your vehicle is equipped with the seven-wire trailer
towing harness. This harness with a seven
-pin universal
heavy
-duty trailer connector that is attached to a bracket
on the hitch platform (if equipped).

4-64
The seven-wire harness contains the following
trailer circuits:

Yellow: Left Stop/Turn Signal

Dark Green: Right Stop/Turn Signal

Brown: Taillamps

White: Ground

Light Green: Back
-up Lamps

Red: Battery Feed

Dark Blue: Trailer Brake
A jumper harness for an electric trailer brake controller
and a trailer battery feed fuse are included with this
trailering package. (See ªInstrument Panel Jumper
Wiring Harnessº later in this section.)
If you need to tow a light
-duty trailer with a standard
four
-way round pin connector, an adapter connector is
available from your dealer.Instrument Panel Jumper Wiring Harness
This harness is included with the heavy-duty trailer
wiring package. The harness is for an electric trailer
brake controller and includes a trailer battery feed fuse.
This harness and fuse should be installed by your dealer
or a qualified service center.

5-3
Jump Starting
If your battery has run down, you may want to use
another vehicle and some jumper cables to start your
vehicle. But please use the following steps to do it safely.
CAUTION:
Batteries can hurt you. They can be
dangerous because:

They contain acid that can burn you.

They contain gas that can explode or ignite.

They contain enough electricity to burn you.
If you don't follow these steps exactly, some or
all of these things can hurt you.
NOTICE:
Ignoring these steps could result in costly damage
to your vehicle that wouldn't be covered by
your warranty.
The ACDelco battery in your vehicle has a
built
-in hydrometer. Do not charge, test or jump
start the battery if the hydrometer looks clear
or light yellow. Replace the battery when there
is a clear or light yellow hydrometer and a
cranking complaint.
Trying to start your vehicle by pushing or pulling
it won't work, and it could damage your vehicle.

5-4
1. Check the other vehicle. It must have a 12-volt
battery with a negative ground system.
NOTICE:
If the other system isn't a 12-volt system with a
negative ground, both vehicles can be damaged.
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 the transmission in
PARK (P). If you have a four
-wheel-drive vehicle,
be sure the transfer case is not in NEUTRAL (N).3. Turn off the ignition on both vehicles. Unplug
unnecessary accessories plugged into the cigarette
lighter or accessory power outlets. Turn off all lamps
that aren't needed as well as radios. This will avoid
sparks and help save both batteries. In addition,
it could save your radio!
NOTICE:
If you leave your radio on, it could be badly
damaged. The repairs wouldn't be covered by
your warranty.
CAUTION:
An electric fan can start up even when the engine
is not running and can injure you. Keep hands,
clothing and tools away from any underhood
electric fan.