1999 GMC C-SERIES ECO mode

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2-9
NOTICE:
Your engine is designed to work with the
electronics in your vehicle. If you add electrical
parts or accessories, you could change the way
the engine operates. Before adding electrical
equipment, check with your dealer. If you don't,
your engine might not perform properly.
If you ever have to have your vehicle towed, see
the part of this manual that tells how to do it
without damaging your vehicle. See ªTowing
Your Vehicleº in the Index.
Gasoline Engine Warm-Up
When you've started your engine, let it run for 20 or
30 seconds to warm up before you put a load on
the engine.
Drive at moderate speeds for the first few miles,
especially in cold weather. Running a cold engine at
high speed can damage it.
Restarting the Gasoline Engine While
Moving (Automatic Transmission)
If you have to restart the engine while the vehicle is
moving, you'll first have to shift the automatic
transmission to NEUTRAL (N). This safety feature
prevents starting the engine when the transmission is in
a drive gear.
Stopping the Gasoline Engine
Let your engine idle for a few seconds before turning it
off after you have finished driving your vehicle.
If you shift to NEUTRAL (N), set the parking brake.
If you shift to PARK (P), the auto
-apply feature will set
the parking brake.
If your vehicle has a two
-speed axle, put the range
selector in LOW. To be sure the axle has shifted into
LOW, engage the clutch and transmission the vehicle
may move slightly when you do this.
While your engine is idling before you turn it off, you
can make a list of any operational or handling concerns
to give to responsible maintenance personnel so they can
handle them right away.
Moisture will condense in a fuel tank that is almost
empty if the vehicle is not run for a while, even just
overnight under some conditions. So, it's always best to
refuel your vehicle at the end of each run.
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2-65
This light should come on when the ignition is on, but
the engine is not running, as a check to show you it is
working. If it does not come on at all, have it repaired.
NOTICE:
If you keep driving your vehicle with this light
on, after a while, your emission controls may not
work as well, your fuel economy may not be as
good and your engine may not run as smoothly.
This could lead to costly repairs that may not be
covered by your warranty.
Engine Oil Pressure Gage
Gasoline Engine Diesel Engine
The engine oil pressure gage, on the lower right portion
of your instrument cluster, shows engine oil pressure
in psi (pounds per square inch) or in kPa (kilopascals).
Oil pressure may vary with outside temperature and oil
viscosity, but readings of 30 to 40 psi (205 to 275 kPa)
on gasoline engines at operating temperature and
moderate road speeds are normal. If you have a diesel
engine, the normal operating range should be between
35 and 70 psi (240 to 480 kPa).
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3-5
OFF
Press this button to turn the air conditioning/heating
system off. Pressing OFF will erase the present mode of
operation from the system's memory. Outside air will
still come out of the heater outlet whenever the vehicle
is moving forward.
If the OFF button is pressed, you must press A/C,
MAX or one of the BLEND buttons to turn the system
back on.
Air Conditioning
When you first turn on your vehicle's air conditioning,
open the windows long enough to clear the vehicle of
hot air, then close them. Using the MAX button can also
help. See ªMAX Buttonº earlier in this section for
more information.
For normal cooling on hot days, use A/C with the
temperature selector toward C.
When you press the A/C button to turn the air
conditioner off, the system will operate in the vent
mode. When you turn the air conditioner back on, the
system will operate in the mode you last selected unless
the OFF button was pressed.If your air conditioner develops high system pressure, it
will automatically go into the MAX mode and REC will
light on your display. The A/C system will remain in the
MAX mode, even if you press the MAX button, until
system pressure returns to a normal level.
Heating
On cold days, use HEATER with the temperature
selector all the way toward H. When the inside of the
vehicle has reached a comfortable temperature, maintain
it by using the temperature selector bar.
If your vehicle is equipped with a diesel engine, and the
engine has been idling for a long time when it's cold
outside, your heater may blow out cool air. This is
normal. When you increase the engine speed under load,
your heater should blow out warmer air. If it doesn't,
your coolant level may be low. See ªEngine Coolantº in
the Index to check your coolant level.
While idling your diesel engine, you can use the MAX
button to recirculate the air in the cab to help maintain
interior heat. This will preserve engine coolant temperature
and cab heat when idling cannot be avoided.
Using the MAX button while driving is not recommended
because interior window fogging can result.
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6-74
Replacement Bulbs
It is recommended that you use an AC
type bulb
whenever you need to replace one.
Before you replace any bulbs, be sure that all lamps are
off and the engine isn't running.
Capacities and Specifications
Replacement part numbers listed in this section are
based on the latest information available at the time of
printing. They are subject to later change. If a part listed
here isn't the same as the part in your vehicle when it
was built, or if you have any questions, please contact
your GM Truck dealer.
Engine Identification and Data
Engine RPO LG5 LP4/L21
Engine Type 7.2L L6 7.4L V8
Fuel System HEUI SPFI
Firing Order
1
-5-3-6-2-41-8-4-3-6-5-7-2
Wheel Nut Torque
Refer to ªTightening the Wheel Nutsº in this section for
wheel nut torque information.
Cooling System Capacity
Model Quarts (Liters)
7.2L 32.0 (30.0). . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
with automatic transmission 30.0 (28.4). . . . . . . . . .
7.4L 25.0 (23.7). . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
with automatic transmission 23.0 (22.7). . . . . . . . . .
Above capacities (volumes) are approximate.
Crankcase Capacity
Capacities (volumes) shown are for normal refill. Add
oil as indicated when the oil filter element is changed.
Capacities given are approximate
-- keep level within
the operating range. Do not operate with fluid level
below the ADD line.
Engine
Capacity
-- Quarts (Liters)
7.2L 21 (19.0)*
7.4L 8 (7.5)
*Additional oil is required with auxiliary oil filter
systems. Make sure to add enough extra oil to fill the
auxiliary oil filter system. For vehicles equipped with
the LUBERFINER 750
-C, add 14 quarts (13.25 L).
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7-27
Door Latches Check
Check that doors close, latch and lock tightly. Check for
broken, damaged or missing parts that might prevent
tight latching.
Hood Latches Check
Check that the hood closes firmly. Check for broken,
damaged, loose or missing parts that might prevent tight
latching. Make sure the secondary latch (if equipped)
keeps the hood from opening all the way when the
primary latch is released.
Fluid Leaks Check
Check for fuel, coolant, oil or other fluid leaks by
looking at the surface beneath the vehicle after it has
been parked for a while.
Underbody Inspection
Corrosive materials used for ice, snow removal and dust
control can collect on the underbody. If these materials
are not removed, accelerated corrosion (rust) can occur
on underbody parts such as fuel lines, frame, floor pan
and exhaust system. At least every spring, flush these materials from the underbody with plain water. Take
care to clean well any areas where mud and other debris
can collect. Sediment packed in closed areas of the
frame should be loosened before being flushed.
Engine Cover Check
Check that the cab's engine cover and seal (if equipped)
are not torn or damaged. Be sure that the cover is bolted
down firmly to the floor.
At Least Once a Year
Key Lock Cylinders Service
Lubricate the key lock cylinders with the lubricant
specified in Part C.
Underbody Flushing Service
At least every spring, use plain water to flush any
corrosive materials from the underbody. Take care to
clean thoroughly any areas where mud and other debris
can collect.
Tractor Protection (Breakaway) Valve Check
On air brake models, remove, disassemble, clean and
inspect the tractor protection (breakaway) valve.
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9-6
Lamps 2-43 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dome 2-46 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
On Reminder 2-44 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Latches, Seatback 1-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Leaving Your Vehicle 2-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lighter 2-47 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lights
Air Brake System Warning 2
-59 . . . . . . . . . . . . . . . . . . . . .
Anti-Lock Brake System Warning 2-61, 4-7 . . . . . . . . . . . .
Apply Park Brake Warning 2-60 . . . . . . . . . . . . . . . . . . . . .
Brake System Warning 2-57 . . . . . . . . . . . . . . . . . . . . . . . . .
Charging System Indicator 2-56 . . . . . . . . . . . . . . . . . . . . . .
Check Gages Indicator 2-67 . . . . . . . . . . . . . . . . . . . . . . . . .
Daytime Running Lamps Indicator 2-67 . . . . . . . . . . . . . . .
Diff Lock Indicator 2-63 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Do Not Shift Warning 2-57 . . . . . . . . . . . . . . . . . . . . . . . . .
Hydraulic Brake System Warning 2-58 . . . . . . . . . . . . . . . .
Intake Heater Indicator 2-63 . . . . . . . . . . . . . . . . . . . . . . . . .
Lamp and Bulb Data 6-74 . . . . . . . . . . . . . . . . . . . . . . . . . .
Low Coolant Warning 2-62 . . . . . . . . . . . . . . . . . . . . . . . . .
Parking Brake Warning 2-60 . . . . . . . . . . . . . . . . . . . . . . . .
Parking Brake Indicator 2-60 . . . . . . . . . . . . . . . . . . . . . . . .
Safety Belt Reminder 1-7, 2-55 . . . . . . . . . . . . . . . . . . . . . .
Service Park Brake Warning 2-60 . . . . . . . . . . . . . . . . . . . .
Service Trans Filter Indicator 2-64 . . . . . . . . . . . . . . . . . . . .
Manual Fast Idle Indicator Light 2-62 . . . . . . . . . . . . . . . . .
Loading Your Vehicle 4-28 . . . . . . . . . . . . . . . . . . . . . . . . . . . Locks
Door 2
-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Door 2-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lubricants and Fluids 7-28 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lubrication Service, Body 7-24 . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance Record 7-31 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Owner Checks and Services 7-23 . . . . . . . . . . . . . . . . . . . . .
Recommended Fluids and Lubricants 7-28 . . . . . . . . . . . . .
Scheduled Maintenance Services 7-4 . . . . . . . . . . . . . . . . . .
Maintenance, Underbody 6-65 . . . . . . . . . . . . . . . . . . . . . . . . .
Malfunction Indicator Lamp 2-64 . . . . . . . . . . . . . . . . . . . . . .
Manual Fast Idle Indicator Light 2-62 . . . . . . . . . . . . . . . . . . .
Manual Transmission Fluid 6-19 . . . . . . . . . . . . . . . . . . . . . . .
Marker and Clearance Lamps 2-45 . . . . . . . . . . . . . . . . . . . . .
Maxi-Fuse Block 6-72 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mirrors
Convex Outside 2
-46 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Heated Outside 2-47 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inside Rearview 2-46 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Outside 2-46 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Model Reference vi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Moisture Ejector 6
-33 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mountain Roads 4-22 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Muffler/Catalytic Converter Assembly 6-48 . . . . . . . . . . . . . .
Multifunction Lever 2-32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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