locks GMC SIERRA 1999 User Guide

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2-22 Front Axle Locking Feature
The front axle locks and unlocks automatically when
you shift the transfer case. Some delay for the axle to
lock or unlock is normal.
Manual Transfer Case (If Equipped)
The transfer case shift lever is on the floor to the right of
the driver. Use this lever to shift into and out of
four
-wheel drive.
The front axle portion of the indicator diagram will light
up when you shift into four
-wheel drive and the front
axle engages.
Some delay between shifting and the indicator's lighting
is normal. If the front axle light does not go out
immediately after you shift out of four
-wheel drive,
have your dealer check your system.
An indicator near the lever shows you the transfer
case settings:
2
-Wheel High (2H): This setting is for driving in most
street and highway situations. Your front axle is not
engaged in two
-wheel drive.

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4-42 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, or
if your vehicle is in gear, for a manual
transmission. You or others could be injured.
Make sure the parking brake is firmly set before
you shift the transfer case into NEUTRAL (N).
Vehicles equipped with the electronic transfer case
cannot be towed with all four wheels on the ground.
Use the following procedure to correctly tow your
vehicle on all four wheels with a manual transfer case:
1. Firmly set the parking brake.
2. Place the transmission in PARK (P) or a manual
transmission in FIRST (1).
3. Securely attach the vehicle being towed to the
tow vehicle.
4. With the engine running, 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.
5. Release the parking brake only after the vehicle
being towed is firmly attached to the towing vehicle.
6. Turn the ignition to OFF. The OFF position unlocks
the steering column and reduces battery drain.
Unlocking the steering column will allow the proper
movement of the front wheels and tires during towing.

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5-20
Changing a Flat Tire
If a tire goes flat, avoid further tire and wheel damage
by driving slowly to a level place. Turn on your hazard
warning flashers.
CAUTION:
Changing a tire can cause an injury. The vehicle
can slip off the jack and roll over you or other
people. You and they could be badly injured.
Find a level place to change your tire. To help
prevent the vehicle from moving:
1. Set the parking brake firmly.
2. Put an automatic transmission shift
lever in PARK (P) or shift a manual
transmission to FIRST (1) or
REVERSE (R).
3. If you have a four
-wheel-drive vehicle,
be sure the transfer case is in a drive
gear
-- not in NEUTRAL (N).
4. Turn off the engine.
CAUTION: (Continued)
CAUTION: (Continued)
To be even more certain the vehicle won't move,
you can put blocks at the front and rear of the
tire farthest away from the one being changed.
That would be the tire on the other side of the
vehicle, at the opposite end.
The following steps will tell you how to use the jack and
change a tire.

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6-42
4. Pull the socket out of the
lamp assembly.
5. Push in gently on
the bulb, turn it
counterclockwise
and remove it from
the socket.
6. Put the new bulb into the socket, gently press in on
the bulb and turn it clockwise until it is tight.
7. Put the socket back into the lamp assembly and turn
it clockwise until it locks.
8. Put the parking/turn signal lamp assembly back into
the vehicle and tighten the screws.Front Turn Signal Lamps
(Composite Headlamps)
1. Remove the four screws
and take out the
parking/turn signal
lamp assembly.
2. Squeeze the tab on the side of the lamp socket while
turning the socket counterclockwise.

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6-43
3. Pull the socket out of
the lamp assembly.
4. Push in gently on the bulb, turn it counterclockwise
and remove it from the socket.
5. Put the new bulb into the socket, gently press in on
the bulb and turn it clockwise until it is tight.
6. Put the socket back into the lamp assembly and turn
it clockwise until it locks.
7. Put the parking/turn signal lamp assembly back into
the vehicle and tighten the four screws.Front Sidemarker Lamps
(Composite Headlamps)
1. Remove the four screws
and pull out the
parking/turn signal
lamp assembly.
2. Reach through the opening and turn the sidemarker
bulb socket counterclockwise and remove it.

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7-43
Hydraulic Clutch System Check
Check the fluid level in the clutch reservoir. See
ªHydraulic Clutch Fluidº in the Index. A fluid loss in
this system could indicate a problem. Have the system
inspected and repaired at once.
At Least Once a Year
Key Lock Cylinders Service
Lubricate the key lock cylinders with the lubricant
specified in Part D.
Body Lubrication Service
Lubricate all fuel doors, body hood and body door
hinges, tailgate and tailgate handle pivot points, latches,
locks and folding seat hardware. Part D tells you what to
use. More frequent lubrication may be required when
exposed to a corrosive environment.Starter Switch Check
CAUTION:
When you are doing this check, the vehicle could
move suddenly. If it does, you or others could be
injured. Follow the steps below.
1. Before you start, be sure you have enough room
around the vehicle.
2. Firmly apply both the parking brake (see ªParking
Brakeº in the Index if necessary) and the regular
brake.
NOTE: Do not use the accelerator pedal, and be
ready to turn off the engine immediately if it starts.
3. On automatic transmission vehicles, try to start the
engine in each gear. The starter should work only in
PARK (P) or NEUTRAL (N). If the starter works in
any other position, your vehicle needs service.
On manual transmission vehicles, put the shift lever
in NEUTRAL (N), push the clutch down halfway
and try to start the engine. The starter should work
only when the clutch is pushed down all the way to
the floor. If the starter works when the clutch isn't
pushed all the way down, your vehicle needs service.

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8-6
Roadside Assistance
GMC's Roadside Assistance provides stranded owners
with over
-the-phone roadside repairs, location of the
nearest GMC dealer or the following special services:
Flat Tire Change: Installation of spare tire will be
covered at no charge (customer is responsible for repair
or replacement of tire).Fuel Delivery: Delivery of enough fuel for the customer
to get to the nearest service station (up to $4.00) will
be covered.
Jump Start: No
-start situations which require a battery
jump start will be covered at no charge.
Lock Out: Replacement keys or locksmith service will
be covered at no charge if you are unable to gain entry
into your vehicle. Delivery of the replacement key will
be covered at no charge within 10 miles (16 km).
Emergency Towing Service: Towing to the nearest
GMC dealer for warranty related disablements will
be covered.
Deluxe Trip Routing: Custom
-made, computerized
highlighted maps using the most direct or scenic route
are provided free of charge. Maps include points of
interest and a list of GMC dealers along the route. Also
included is a list of hotels along the route that are
discounted through affiliation with ªQuest
International.º Trip Routing is available through
Roadside Assistance by calling 1
-800-GMC-8782
(462-8782). Please be prepared to provide your Vehicle
Identification Number (VIN). Allow five working days
for fulfillment.

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9-3
Wheels 6-67 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Windshield and Wiper Blades 6-64 . . . . . . . . . . . . . . . . . . .
Climate Control System 3-2, 3-3 . . . . . . . . . . . . . . . . . . . . . . .
Clock, Setting the 3-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Clutch Fluid, Hydraulic 6-24, 7-48 . . . . . . . . . . . . . . . . . . . . .
Clutch, System Check 7-42 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Comfort Controls 3-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Comfort Guides, Rear 1-43 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Compact Disc Care 3-27 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Compact Disc Player 3-17, 3-21 . . . . . . . . . . . . . . . . . . . . . . .
Compact Disc Player Care 3-27 . . . . . . . . . . . . . . . . . . . . . . . .
Compass, Rearview Mirror with 2-45 . . . . . . . . . . . . . . . . . . .
Console Storage 2-53 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Control of a Vehicle 4-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Convex Outside Mirror 2-50 . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant 6-28, 6-76, 7-48 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Heater, Engine 2-15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Recovery Tank 5-11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cooling System 5-11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Courtesy Transportation 8-8 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cruise Control 2-38 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cupholders 2-53, 2-54, 2-55 . . . . . . . . . . . . . . . . . . . . . . . . . .
Customer Assistance for Text Telephone Users 8-4 . . . . . . . . .
Customer Assistance Information 8-1 . . . . . . . . . . . . . . . . . . .
Customer Satisfaction Procedure 8-2 . . . . . . . . . . . . . . . . . . . .
Damage, Finish 6-67 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Damage, Sheet Metal 6-67 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Daytime Running Lamps 2-42 . . . . . . . . . . . . . . . . . . . . . . . . .
Daytime Running Lamps Indicator Light 2-74 . . . . . . . . . . . .
Dead Battery 5-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Defects, Reporting Safety 8
-10 . . . . . . . . . . . . . . . . . . . . . . . .
Defensive Driving 4-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Defogger, Rear Window 3-6 . . . . . . . . . . . . . . . . . . . . . . . . . .
Defogging and Defrosting 3-6 . . . . . . . . . . . . . . . . . . . . . . . . .
Dolby Noise Reduction 3-15 . . . . . . . . . . . . . . . . . . . . . . . . . .
Dome Lamps 2-43 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Door
Locks 2
-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage Pocket 2-50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Third 2-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Downshifting 2-21 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Driver Position 1-14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Driving
City 4
-31 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Defensive 4-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Drunken 4-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Freeway 4-32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
In a Blizzard 4-38 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
In the Rain 4-28 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Night 4-27 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Off-Road 4-14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
On Curves 4-9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
On Grades While Towing a Trailer 4-58 . . . . . . . . . . . . . . .
On Hill and Mountain Roads 4-34 . . . . . . . . . . . . . . . . . . . .
On Snow and Ice 4-37 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Through Water 4-30 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wet Roads 4-28 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Winter 4-36 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
With a Trailer 4-56 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Drunken Driving 4-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dual Tire Operation 6-55 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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9-4
Easy Entry Seat 1-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical Equipment, Adding 2-13, 3-27, 6-69 . . . . . . . . . . .
Electrical System 6-69 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrochromic Day/Night Rearview Mirror 2-45 . . . . . . . . . .
Engine 6-10, 6-11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Air Cleaner/Filter 6-17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant 6-28, 6-76, 7-48 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant Heater 2-15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant Level Check 7-41 . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant Temperature Gage 2-69 . . . . . . . . . . . . . . . . . . . . .
Cooling System Capacity 6-77 . . . . . . . . . . . . . . . . . . . . . . .
Exhaust 2-31, 4-40 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuse Blocks 6-70, 6-73 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Identification 6-69 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Oil Level Check 7-41 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Overheating 5-9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Running While Parked 2-31 . . . . . . . . . . . . . . . . . . . . . . . . .
Specifications 6-76 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Starting Your 2-13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Underhood Fuse/Relay Center 6-73 . . . . . . . . . . . . . . . . . . .
Engine Oil 6-13, 7-48 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Adding 6-14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Additives 6-16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Checking 6-14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pressure Gage 2-72 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Used 6-17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
When to Change 6-16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Exhaust, Engine 2-30, 4-40 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fabric Cleaning 6-61 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fan Control, Climate Control System 3-2, 3-3 . . . . . . . . . . . .
Fender Marker Lamp Bulb Replacement 6-44 . . . . . . . . . . . . .
Filling a Portable Fuel Container 6-8 . . . . . . . . . . . . . . . . . . . .
Filling Your Tank 6-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filter, Air 6-17, 6-78 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Finish Care 6-65 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Finish Damage 6-67 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Flashers, Hazard Warning 5-2 . . . . . . . . . . . . . . . . . . . . . . . . .
Flat Tire, Changing 5-20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fluid Capacities 6-77 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fluids and Lubricants 7-48 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Foreign Countries, Fuel 6-5 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Four-Wheel Drive 2-21, 6-26 . . . . . . . . . . . . . . . . . . . . . . . . .
French Language Manual ii. . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Axle 6
-27, 7-49 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Axle Locking Feature 2-22 . . . . . . . . . . . . . . . . . . . . . . .
Front Towing 5-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Turn Signal Lamp Bulb Replacement 6-41, 6-42 . . . . .
Fuel 6-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filling a Portable Container 6-8 . . . . . . . . . . . . . . . . . . . . . .
Filling Your Tank 6-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gage 2-75 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
In Foreign Countries 6-5 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tank Capacity 6-77 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuses and Circuit Breakers 6-70 . . . . . . . . . . . . . . . . . . . . . . .
Fusible Links 6-70 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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9-6
Jack, Tire 5-21 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Jump Starting 5-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Key Lock Cylinders Service 7-43 . . . . . . . . . . . . . . . . . . . . .
Key Release Button 2-13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Keyless Entry System 2-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Keys 2-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Labels
Certification 4-43 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Certification/Tire 4-43 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Service Parts Identification 6-69 . . . . . . . . . . . . . . . . . . . . .
Vehicle Identification Number 6-69 . . . . . . . . . . . . . . . . . . .
Lamps 2-41 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cargo 2-44 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning 6-65 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dome 2-43 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Exterior 2-41 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Interior 2-42 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
On Reminder 2-41 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Latches, Seatback 1-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Leaving Your Vehicle 2-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Leaving Your Vehicle with the Engine Running 2-28 . . . . . . .
Lighter 2-58 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lights
Air Bag Off 2
-65 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Air Bag Readiness 1-25, 2-65 . . . . . . . . . . . . . . . . . . . . . . .
Anti-Lock Brake System Warning 2-69, 4-7 . . . . . . . . . . . .
Brake System Warning 2-68 . . . . . . . . . . . . . . . . . . . . . . . . .
Charging System 2-67 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Check Gages 2
-74 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Daytime Running Lamps Indicator 2-74 . . . . . . . . . . . . . . .
Safety Belt Reminder 1-9, 2-64 . . . . . . . . . . . . . . . . . . . . . .
Security 2-73 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Service Engine Soon 2-70 . . . . . . . . . . . . . . . . . . . . . . . . . .
Shift 2-21, 2-74 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Loading Information, Truck-Camper 4-45 . . . . . . . . . . . . . . .
Loading Your Vehicle 4-43 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Loading Your Vehicle for Off-Road Driving 4-14 . . . . . . . . . .
Lockout Switch 2-34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Locks
Cylinders 7
-43 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Door 2-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ignition Transmission Check 7-44 . . . . . . . . . . . . . . . . . . . .
Key Lock Cylinders Service 7-43 . . . . . . . . . . . . . . . . . . . .
Power Door 2-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lubricants and Fluids 7-48 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lubrication, Weatherstrips 6-64, 7-42 . . . . . . . . . . . . . . . . . . .
Lubrication Service, Body 7-43 . . . . . . . . . . . . . . . . . . . . . . . .
Lumbar Controls 1-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance, Normal Replacement Parts 6-78 . . . . . . . . . . .
Maintenance Record 7-52 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance Schedule 7-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Long Trip/Highway Definition 7-6 . . . . . . . . . . . . . . . . . . .
Long Trip/Highway Intervals 7-7 . . . . . . . . . . . . . . . . . . . . .
Owner Checks and Services 7-41 . . . . . . . . . . . . . . . . . . . . .
Periodic Maintenance Inspections 7-46 . . . . . . . . . . . . . . . .
Recommended Fluids and Lubricants 7-48 . . . . . . . . . . . . .
Scheduled Maintenance Services 7-4 . . . . . . . . . . . . . . . . . .
Short Trip/City Definition 7-5 . . . . . . . . . . . . . . . . . . . . . . .
Short Trip/City Intervals 7-6 . . . . . . . . . . . . . . . . . . . . . . . .