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Relay Usage
PTO Power Take-Off
REVERSE Reverse
NEUTRAL
STARTNeutral Start
Fuse Usage
RR DEFOG Rear Defog
ENG 1 Engine 1
ENG 3 Engine 3
PCM-B Powertrain Control Module
BLANK Empty
ENG 4 Engine 4
ENG 2 Engine 2
HTD FUEL Heated Fuel
BLANK EmptyFuse Usage
BLANK Empty
BLANK Empty
A/C COMP Air Conditioning Compressor
ABS 1 Anti-Lock Brake System 1
ABS 2 Anti-Lock Brake System 2
ABS 3 Anti-Lock Brake System 3
ENGINE Engine
E/A PUMP Electronic/Automatic Pump
HORN Horn
NOTE 2L18/LB7 Fuel, LG4 Powertrain
Control Valve, LG5 Electronic
Control Module
BLANK Empty
STUD A Spare
STUD B Spare
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Fuse Usage
IGN 1 Ignition 1
IGN 4 Ignition 4
IGN 3 Ignition 3
BATT/HAZ Battery/Hazard Warning Flashers
HEADLAMP Headlamps
LIGHTING Interior/Exterior Lamps
HVAC Comfort Control System
NOTE C4/C5 Electric Brake,
C6/C7/C8 Brake Lamps
Capacities and Speci cations
Capacities and Speci cations
Engine RPO
7.2L L6 HEUI Fuel System LG5
8.1L V8 SPFI Fuel System L18
7.8L L6 Common Rail Fuel System LG4
6.6L V8 Common Rail Fuel System LB7/LLY Secondary Underhood
Fuse Block
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Engine Oil with Filter Capacity
ApplicationCapacities
English Metric
7.2L** 30.0 quarts 28.4 liters*
8.1** 6.5 quarts 6.1 liters
7.8L** 23.8 quarts 22.5 liters
6.6L** 14.6 quarts 13.8 liters
*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).
**Check fill level on the oil indicator after initial fill to make sure it is actually full. Oil level may vary depending on
vehicle option content.
Fuel Tank Capacity
ApplicationCapacities
English Metric
C4/C5 Models
Standard*
Optional
Optional
Optional40 gallons
40 gallons
60 gallons
80 gallons151.4 liters
151.4 liters
227.1 liters
302.8 liters
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Fuel Tank Capacity (cont’d)
ApplicationCapacities
English Metric
C6/C7/C8 Models
Standard
Optional
Optional
Optional†
Optional**
Optional&50 gallons
35 gallons
50 gallons
70 gallons
75 gallons
100 gallons189.2 liters
132.4 liters
189.2 liters
264.8 liters
283.8 liters
378.5 liters
*One 25-gallon (94.6 L) tank and one 15-gallon (56.8 L) tank
†Two 35-gallon (132.4 L) tanks
**One 25-gallon (94.6 L) tank and one 50-gallon (189.2 L) tank
&Two 50-gallon (189.2 L) tanks
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Part Engine
(RPO Code)GM Part
NumberACDelco®Part
NumberOther Part
Numbers
Engine Air Cleaner/Filter
6.6L (LB7/LLY) (C4/C5 Models)
6.6L (LB7/LLY) (C6/C7/C8 Models)
7.2L (LG5)
7.8L (LG4) (C4/C5 Models)
7.8 L (LG4) (C6/C7/C8 Models)
8.1L (L18)88937527
88937548***
—
8837527
88937548***
25313349—
—
—
—
—
A1518C—
—
Donaldson P522606
—
—
—
Engine Oil Filter
6.6L (LB7/LLY)
7.2L (LG5)
7.8L (LG4)
8.1L (L18)88917036
—
94392475
89028862PF2232
—
—
PF454—
CAT 1R0739
—
—
Fuel Filter
6.6L (LB7/LLY)
7.2L (LG5)
7.8L (LG4)
8.1L (L18)97256734
—
94392474
——
915 Primary**
—
GF626*—
—
—
—
Power Steering Fluid Filter
6.6L (LB7/LLY)
7.2L (LG5)
7.8L (LG4)
8.1L (L18)88892858
88892858
88892858
88892858—
—
—
——
—
—
—
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Part Engine
(RPO Code)GM Part
NumberACDelco®Part
NumberOther Part
Numbers
Pressure Caps
6.6L (LB7/LLY)
7.2L (LG5)
7.8L (LG4)
8.1L (L18)15075118
—
15075118
15997145—
—
—
——
—
—
—
Secondary Fuel Filter
6.6L (LB7/LLY)
7.2L (LG5)
7.8L (LG4)
8.1L (L18)—
—
15098649
25055052—
—
—
——
CAT 1R0751
—
—
Spark Plugs
6.6L (LB7/LLY)
7.2L (LG5)
7.8L (LG4)
8.1L (L18)—
—
—
——
—
—
41-983—
—
—
—
*Optional Davco (K28) D350921 spin-on type filter located on driver’s side frame rail.
**Optional Cold Weather (KUK) Racor B6484GM spin-on type filter located on driver’s side frame rail.
***Optional air filter (GM Part No. 88937525) for C6/C7/C8 Models. Fits inside standard size filter (GM Part No.
88937548) listed previously.
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Maintenance Schedule......................................6-2
Introduction...................................................6-2
Maintenance Requirements..............................6-2
Your Vehicle and the Environment....................6-2
How This Section is Organized.........................6-3
Part A: Scheduled Maintenance Services...........6-4
Using Your Maintenance Schedule....................6-4
Scheduled Maintenance Supplements................6-4Scheduled Maintenance...................................6-5
Part B: Owner Checks and Services................6-24
At Each Fuel Fill..........................................6-24
At Least Twice a Year...................................6-25
At Least Once a Year...................................6-28
Part C: Recommended Fluids and Lubricants. . . .6-29
Part D: Maintenance Record..........................6-31
Section 6 Maintenance Schedule
6-1
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Part A: Scheduled Maintenance
Services
In this part are scheduled maintenance services which
are to be performed at the mileage intervals specified.
Using Your Maintenance Schedule
We at General Motors want to help keep your vehicle in
good working condition. But we do not know exactly
how you will drive it. You may drive very short distances
only a few times a week. Or you may drive long
distances all the time in very hot, dusty weather. You
may use your vehicle in making deliveries or in
many other ways.
Because of all the different ways people use their
vehicles, maintenance needs vary. You may need more
frequent checks and replacements. So please read
the following and note how you drive. If you have any
questions on how to keep your vehicle in good condition,
see your dealer.
This part tells you the maintenance services you should
have done and when to schedule them.
When you go to your dealer for your service needs, you
will know that GM-trained and supported service
people will perform the work using genuine GM parts.The proper fluids and lubricants to use are listed in
Part C. Make sure whoever services your vehicle uses
these. All parts should be replaced and all necessary
repairs done before you or anyone else drives the
vehicle.
This schedule is for vehicles that:
•carry passengers and cargo within recommended
limits. You will find limits on your vehicle’s GVW
Rating label. SeeLoading Your Vehicle on
page 4-33.
•are driven on reasonable road surfaces within legal
driving limits.
•use the recommended fuel. SeeWhat Fuel to Use
on page 5-8.
Scheduled Maintenance
Supplements
If your vehicle has a Caterpillar®diesel engine, your
owner’s manual is supplemented by the Caterpillar®
Diesel Engine Operation & Maintenance Manual. If your
vehicle has an Allison transmission, your owner’s
manual is supplemented by an Allison
Transmission
®Operator’s Manual. Always refer to these
manuals for related maintenance services.
6-4