2008 DODGE RAM 2500 DIESEL engine

experience reduced performance, an elevated/rough idle
or engine stall and your vehicle may require towing. The
light will come on when the ignition is first turned on
and remain on for 15 seconds as a bulb check. If the light
does not come on during starting, have the system
checked by an authorized dealer.
22. SERV 4WD Indicator
The 4WD indicator will be illuminated whenever the
4WD mode is engaged for either the manual or electric
shift 4WD systems. The SERV 4WD indicator monitors
the electric shift 4WD system. If the SERV 4WD light
stays on or comes on during driving, it means that the
4WD system is not functioning properly and that service
is required.23. Water In Fuel Indicator
Indicates there is water detected in the fuel
filter. Refer to the Maintenance section, Drain-
ing Fuel/Water Separator Filter, for water
drain procedure.
24. Tire Pressure Monitoring Telltale Light Ð If
Equipped
Each tire, including the spare (if provided),
should be checked monthly when cold and
inflated to the inflation pressure recommended
by the vehicle manufacturer on the vehicle
placard or tire inflation pressure label. (If your vehicle
has tires of a different size than the size indicated on the
vehicle placard or tire inflation pressure label, you should
determine the proper tire inflation pressure for those
tires.)
196 UNDERSTANDING YOUR INSTRUMENT PANEL

CAUTION!
The TPMS has been optimized for the original
equipment tires and wheels. TPMS pressures and
warning have been established for the tire size
equipped on your vehicle. Undesirable system opera-
tion or sensor damage may result when using re-
placement equipment that is not of the same size,
type, and/or style. Aftermarket wheels can cause
sensor damage. Do not use tire sealant from a can, or
balance beads if your vehicle is equipped with a
TPMS, as damage to the sensors may result.
TPMS ªLight Loadº Reset Switch ± If Equipped
The TPMS ºLight Loadº reset switch allows you to
choose between Light Load vehicle conditions and Max
Load vehicle conditions tire pressures and related TPMS
warning levels. The switch is located in the instrumentpanel, below the climate control panel. For additional
information refer to ªTire Pressure Monitoring System
(TPMS) Ð If Equippedº in section 5 of this manual.
25. Transmission Oil Temperature Warning Light
(Automatic Transmissions Only)
This light indicates that there is excessive trans-
mission fluid temperature that might occur
with severe usage such as trailer towing. It may
also occur when operating the vehicle in a high
torque converter slip condition, such as 4-wheel drive
operation (e.g., snow plowing, off-road operation). If this
light comes on, stop the vehicle and run the engine at idle
or faster, with the transmission in NEUTRAL until the
light goes off.
26. Wait To Start Indicator
The Wait To Start indicator will illuminate when
the ignition is turned to the run position and the
intake manifold temperature is below 66ÉF (19ÉC).
198 UNDERSTANDING YOUR INSTRUMENT PANEL

Follow engine starting procedure for proper engine start-
ing and operating. Wait until the Wait To Start indicator
turns OFF, then start the vehicle.
NOTE:The Wait To Start Indicator may not illuminate if
the engine coolant temperature is warm enough.
27. Odometer/Trip Odometer Button
Press this button to toggle between the odometer and the
trip odometer display. Holding the button in resets the
trip odometer reading when in trip mode.
28. Fuel Gauge
Shows level of fuel in tank when ignition switch is in the
ON position.
29. Low Fuel Warning Light
Glows when the pointer is between ªEº and 1/8
indication mark (approximately 15% of tank vol-
ume) on the fuel gauge. When the fuel gauge
pointer is on ªEº (equivalent to Distance To Empty[DTE]=0ontheoverhead console, if so equipped) there
is reserve fuel capacity, which corresponds to approxi-
mately 8% of tank volume. This reserve capacity was put
in place to prevent the likelihood of customers running
out of fuel when operating at maximum load conditions
in areas where there aren't many fuel stations.
Fuel tank volumes are as follows:
²34 gal (128 L) - 2500/3500 short box models
²35 gal (132 L) - 2500/3500 long box models
30. CRUISE Light
This indicator lights when the electronic speed control
system is turned on.
UNDERSTANDING YOUR INSTRUMENT PANEL 199
4

Air Conditioning and Heating Ð If Equipped
Air Conditioning Operation
To turn on the Air Conditioning, set the fan
control at any speed and press the snowflake
button located at the right of the control panel.
Conditioned air will be directed through theoutlets selected by the mode control. A light in the
snowflake button shows that the air conditioning is on.
Press the button a second time to turn the air condition-
ing off.
Slight changes in engine speed or power may be noticed
when the air conditioning compressor is on. This is a
normal occurrence as the compressor will cycle on and
off to maintain comfort and increase fuel economy.
The mode control (at the right of the
control panel) can be set in any of the
following positions:
Air Conditioning And Heating
252 UNDERSTANDING YOUR INSTRUMENT PANEL

Side window demisters direct airflow specifically to the
window glass to help prevent interior fogging of the
glass. They are located in the extreme outside upper
edges of the instrument panel. The demisters also pro-
vide extra air ducts for circulation. They are in operation
whenever the Floor, Mix or Defrost modes are in use. To
remove frost from the side windows, it is best to use the
full defrost mode.
NOTE:When you turn off the engine you may hear a
hissing sound from under the hood for a short period of
time. This is a normal condition that occurs if the air
conditioning system has been on. It is not an indication of
a problem with the air conditioning system.Air Conditioning with Dual Zone Temperature
Control Ð If Equipped
With the Dual Zone Temperature Control System, each
front seat occupant can independently control the tem-
perature of air coming from the outlets on their side of
the vehicle.
Dual Zone Control Head
UNDERSTANDING YOUR INSTRUMENT PANEL 255
4

Circulation
The cab is designed with features to promote outside air
circulation. There are grilles in the cab back panel. These
are air exhausters that provide the means for regular
exchange of cab air.
Side window demisters direct airflow specifically to the
window glass to help prevent interior fogging of the
glass. They are located in the extreme outside upper
edges of the instrument panel. The demisters also pro-
vide extra air ducts for circulation. They are in operation
whenever the Floor, Mix or Defrost modes are in use.
NOTE:When you turn off the engine you may hear a
hissing sound from under the hood for a short period of
time. This is a normal condition that occurs if the air
conditioning system has been on. It is not an indication of
a problem with the air conditioning system.
Rear Air Duct (Mega Cab Only) Ð If Equipped
The rear seat will receive airflow in all modes except for
Defrost.
The rear air duct is designed to be pointed up when in
A/C mode, and pointed down in Heat mode.
Mega Cab Rear Air Duct
UNDERSTANDING YOUR INSTRUMENT PANEL 259
4

Summer Operation
Air conditioned vehicles must be protected with a high
quality antifreeze coolant during summer to provide
proper corrosion protection and to raise the boiling point
of the coolant for protection against overheating. A 50 %
concentration is recommended. For proper coolant type,
refer to ªRecommended Fluids and Genuine Partsº in
Section 7.
When using the air conditioner in extremely heavy traffic
in hot weather, especially when towing a trailer, addi-
tional engine cooling may be required. If this situation is
encountered, operate the transmission in a lower gear to
increase engine RPM, coolant flow and fan speed. When
stopped in heavy traffic, it may be necessary to shift into
NEUTRAL and depress the accelerator slightly for fast
idle operation to increase coolant flow and fan speed.NOTE:On models equipped with Diesel engines, the
idle speed will automatically increase to 1000 rpm at
elevated coolant temperatures to improve engine cooling.
Your air conditioning system is also equipped with an
automatic recirculation system. When the system senses
a heavy load or high heat conditions, it may use partial
Recirculation A/C mode to provide additional comfort.
Winter Operation
When operating the system during the Winter months,
make sure the air intake, located directly in front of the
windshield, is free of ice, slush, snow, or other obstruc-
tions.
UNDERSTANDING YOUR INSTRUMENT PANEL 261
4

STARTING AND OPERATING
CONTENTS
mStarting Procedures ± Diesel Engines.........268
NAutomatic Transmission ± If Equipped......268
NManual Transmission ± If Equipped........269
NNormal Starting Procedure ± Engine Manifold
Air Temperature Above 66ÉF (19ÉC)........269
NStarting Procedure ± Engine Manifold Air
Temperature Below 66ÉF (19ÉC)...........270
NStarting Fluids.......................274
mNormal Operation (Diesel Engine)...........274
NCold Weather Precautions...............275NEngine Idling........................278
NStopping The Engine...................280
NEngine Speed Control..................281
NOperating Precautions..................281
NCooling System Tips Ð Automatic
Transmission........................281
mDiesel Exhaust Brake (Engine Braking) ±
If Equipped...........................283
mTransmission Shifting....................285
NAutomatic Transmission With Overdrive
(68RFE) Ð If Equipped.................285
5