2003 CHEVROLET C/K coolant temperature

2-20 Cold Weather Starting
(Caterpillar

Diesel)
Because the diesel engine uses compression ignition, it
is harder to start in cold weather than a gasoline engine.
The air intake heater and use of the proper engine oil,
optional engine coolant heaters and optional ether
injection systems help cold weather starting. See the
Caterpillar

Diesel Engine Operation & Maintenance
Manual for more information.
NOTICE:
Your diesel engine has an electric air intake
heater system which reduces white smoke and
helps start the engine in cold weather. Do not
spray starting fluid into the air intake where it
can contact the heater elements.
If you don't have the GM Automatic Ether
Injection System, don't use starting fluid or you
could damage your engine. If you have the GM
system, use only GM approved starting fluid that
has been tested to establish compatibility with the
air inlet heater system.
Diesel Engine Warm-Up
Several factors affect how quickly your diesel engine
warms up. These can include outside temperature,
engine load, idle time and your vehicle's option content.
Your vehicle may be equipped with some features that
can help the engine reach operating temperature sooner.
Some of these features are discussed below.
Also, remember that an automatic transmission adds
heat to the cooling system through the heat exchanger in
the radiator. Because of this, vehicles equipped with
automatic transmissions are often able to retain engine
coolant heat better than manual transmission vehicles.
See your Caterpillar

Operation & Maintenance manual
for additional diesel engine warm
-up information.

2-21 Engine Alarm and Automatic Shutdown
(If Equipped)
Your check gages light will come on if the system senses
high engine temperature or low engine oil pressure. If high
engine temperature or low engine oil pressure is detected,
you will also hear a tone alarm at two beats per second.
The alarm and the light will remain on until the condition
is fixed. If the engine temperature or oil pressure condition
worsens, the tone alarm will go to five beats per second.
If the system senses low engine coolant, the five beat
per second alarm and the low coolant warning light will
come on.
The five beats per second tone alarm means that your
engine will shut down in approximately 25
-30 seconds.
There is also an engine shutdown light to indicate that
the engine will shut down. See ªAutomatic Engine
Shutdown Lightº later in this section.
Pull off the road and shut off the engine. Don't start it
until the reason for the problem is known, and the
problem is fixed. If the engine shuts down when you are
still in traffic, you can restart the engine and get another
25
-30 seconds of operation. Do this only if you have to,
since there is a problem that can harm the engine if it
isn't fixed. Engine automatic shutdown, for gasoline
engines, requires activation by your dealer.
High Idle System (Caterpillar
Diesel
and Gasoline Engines)
Your vehicle has both automatic and manual high idle
capabilities.
Automatic High Idle System (Diesel Engines)
(If Equipped)
The automatic high idle feature will engage whenever
you start your vehicle and the engine is below the preset
operating temperature. This will help decrease engine
warm
-up time.
Idle speed will then return to normal under any of the
following conditions:

The engine reaches the preset operating temperature
or has been operating for at least ten minutes.

The brake pedal is pressed.

The manual transmission clutch pedal is pressed or,
the automatic transmission (if equipped) is shifted
from NEUTRAL (N) or PARK (P).

The vehicle speed exceeds approximately
5 mph (8 km/h).

The throttle is pressed.

2-23 Exhaust Restrictor (Diesel Engines)
(If Equipped)
If your vehicle is equipped with this feature, there is an
exhaust restrictor valve located in the exhaust stream.
The valve closes to provide back pressure to the engine
for the purpose of warming the engine quickly.
The exhaust restrictor operates:

while the engine is running.

while the vehicle is not moving.

while the accelerator, brake and clutch pedals are
not pressed.

while idling or driving in cold temperatures.

when the shift lever is in NEUTRAL (N)
or PARK (P).On vehicles equipped with a diesel engine exhaust
brake, the exhaust brake switch must be on. The
indicator in the exhaust brake switch will be lit when the
exhaust restrictor is active. The exhaust brake indicator
light in the center of the instrument panel will also be lit
whenever the exhaust restrictor is active.
When the engine coolant temperature is below 149F
(65C) and the outside temperature is below 50F
(10C), the exhaust restrictor will come on within
45 seconds of starting the engine. After running the
engine for an additional 45 seconds, the engine idle
will increase.
The exhaust restrictor will shut off and engine idle will
return to normal once the engine is warmed up, or the
transmission is shifted into range.

2-25
NOTICE:
If the wait to start light stays on, it means that
your vehicle could have one of several problems,
so you should have it serviced right away.
3. If the engine does not start after 15 seconds of
cranking, turn the ignition key to OFF. Wait
one minute for the starter to cool, then try the
same steps again.
If you're trying to start your engine after you've run
out of fuel, follow the steps in ªRunning Out of Fuel.º
See ªDiesel Fuel Requirements and Fuel Systemº in
the Index.
When your engine is cold, let it run for a few minutes
before you move your vehicle. This lets oil pressure
build up. Your engine will sound louder when it's cold.
NOTICE:
If you're not in an idling vehicle and the engine
overheats, you wouldn't be there to see the
overheated engine condition. This could damage
your vehicle. Don't let your engine run when
you're not in your vehicle.
Cold Weather Starting (Diesel Engine)
The following tips will help you get good starting in
cold weather.
Use the recommended engine oil when the outside
temperature drops below freezing. See ªEngine Oilº in
the Index. When the outside temperature drops below
0
F (
-18
C), use of the engine coolant heater is
recommended.
If you experience longer cranking times, notice an
unusual amount of exhaust smoke or are at higher
altitudes (over 7,000 ft. or 2 135 m), you may use your
engine coolant heater. See ªEngine Coolant Heaterº in
the Index.
See ªDiesel Fuel Requirements and Fuel Systemº in the
Index for information on what fuel to use in cold weather.

2-27
Engine Checks Before Operating
When you've started your engine, let it run for 20 to
30 seconds before you put a load on the engine. But
don't leave the vehicle while the engine is running.
Avoid unnecessary idling of diesel engine equipped
vehicles.
If the engine idles too long, the temperature of the
engine coolant will fall below the normal operating
range. Low engine operating temperature causes several
conditions which affect engine operation and reduce
engine life.
The engine should be permitted to go through a
warm
-up period. Operate the vehicle at a minimum of
600 rpm during the warm
-up period. During this period
and during operation, the following observations should
be made.
During this warm
-up period, check your warning lights
and gages:

If oil pressure doesn't begin to rise within
15 seconds of starting, stop the engine and
find the cause.
If the engine coolant temperature gage needle goes
into the hot area on the gage, stop the engine and
find the cause of the overheating.

If you have air brakes, the dual
-needle air pressure
gage should read at least 115 psi (790 kPa) for both
service systems before you try to move the vehicle.
When air pressure is below 60 psi (420 kPa), the
LOW AIR light will come on and you will hear a
tone alarm. If the pressure doesn't build up or
drops during warm
-up, stop the engine and find
the cause before you try to move the vehicle.
Recommended air pressure before actually driving
away is 120 psi (830 kPa).

The charging system light should come on when
the ignition key is turned to RUN or START and
should go out when the engine is running above idle.
If the light doesn't go out or comes back on during
normal engine operation, have the charging system
checked right away. (This light tells you if the
generator is not charging; it doesn't reflect the
condition of the battery.)

2-28

The voltmeter charge indicator gage tells you the
condition of your battery's charge. The gage should
be in the center area during engine operation. The
red area on the left indicates an undercharge
condition; the red area on the right indicates an
overcharge. If the gage is in either red area, have the
battery and charging system checked right away.
NOTICE:
For diesel engines, don't allow the engine to
operate at low idle for more than five minutes.
This can cause low engine operating
temperatures which can affect engine operation
and reduce engine life. Engine idle speed should
be increased to 1200 rpm whenever extended idle
is required. Once started, the engine should be
placed under load to allow the engine coolant
temperature to reach 150F (66C) before
shutting off the engine.
Engine Coolant Heater (If Equipped)
If your vehicle is equipped
with this feature, the plug
-in
receptacle is located under
the driver's door.
In very cold weather, 0F (
-18C) or colder, the engine
coolant heater can help. You'll get easier starting and
better fuel economy during engine warm
-up. Usually,
the coolant heater should be plugged in a minimum of
four hours prior to starting your vehicle.

2-29 To Use the Engine Coolant Heater
1. Turn off the engine.
2. Find the plug
-in receptacle (either behind the front
bumper or in the component box).
3. Plug a heavy
-duty, three-prong extension cord
(rated for at least 15 amps) into the vehicle's plug
-in
receptacle first. Then plug the extension cord into a
normal, grounded 110
-volt AC outlet.
CAUTION:
Plugging the cord into an ungrounded outlet
could cause an electrical shock. Also, the wrong
kind of extension cord could overheat and cause
a fire. You could be seriously injured. Plug the
cord into a properly grounded three
-prong
11 0
-volt AC outlet. Use a heavy-duty three-prong
extension cord rated for at least 15 amps.
4. Before starting the engine, be sure to unplug
the cord.
How long should you keep the coolant heater plugged
in? The answer depends on the outside temperature.
From 32
F to
-10
F (0
C to -23
C), keep the coolant
heater plugged in at least two hours. Below
-10
F
(
-23
C), keep the coolant heater plugged in for a
minimum of eight hours or overnight. It will not harm
either the coolant heater or the vehicle to leave the
coolant heater plugged in longer than the times stated.
Be sure to remove and store the cord before starting the
engine. See ªDiesel Fuel Requirements and Fuel
Systemº in the Index for information on what fuel to
use in cold weather.

2-84 Trailer Anti-Lock Brake System
Warning Light
If your vehicle is connected
to an anti
-lock brake system
equipped trailer, this light
should come on briefly, as
a check, when you turn on
the ignition.
When this light comes on and stays on, it means there is
something wrong in the trailer anti
-lock brake system.
Have the system repaired immediately.
If an anti
-lock brake system equipped trailer is not
connected, this light is not functional.
Engine Coolant Temperature Gage
United States Canada
This gage shows the engine coolant temperature. If the
gage pointer moves into the red area, your engine
coolant might have overheated and your engine may be
too hot. You should pull off the road, stop your vehicle
and turn off the engine as soon as possible.
See ªEngine Overheatingº in the Index. If you have a
Caterpillar

diesel engine, also see your Caterpillar

Operation & Maintenance Manual.