1999 CHEVROLET C/K lock

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6-72
Fuse/Circuit
Breaker Usage
3 Courtesy Lamps, Cargo Lamp,
Glove Box Lamp, Dome/Reading
Lamps, Vanity Mirrors,
Power Mirrors
4 Instrument Cluster, DRL Relay,
Lamp Switch, Keyless Entry,
Low Coolant Module, Illuminated
Entry Module,
DRAC (Diesel Engine)
5 Not Used
6 Cruise Control
7 Auxiliary Power Outlet
8 Crank
9 License Lamp, Parking Lamps,
Taillamps, Roof Marker Lamps,
Tailgate Lamps, Front
Sidemarkers, Fog Lamp Relay,
Door Switch Illumination,
Fender Lamps, Headlamp
Switch IlluminationFuse/Circuit
Breaker Usage
10 Not Used
11 Wiper Motor, Washer Pump
12 A/C, A/C Blower,
High Blower Relay
13 Power Amp, Cigarette Lighter,
Door Lock Relay,
Power Lumbar Seat
14 4WD Indicator, Cluster, Comfort
Controls, Instrument Switches,
Radio Illumination,
Chime Module
15 DRL Relay, Fog Lamp Relay
16 Front and Rear Turn Signals,
Back
-Up Lamps, BTSI Solenoid
17 Radio (Ignition)
18 4WAL/VCM, ABS,
Cruise Control
19 Radio (Battery)

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6-73
Fuse/Circuit
Breaker Usage
20 PRNDL, Automatic Transmission,
Speedometer, Check Gages
Warning Light
21 Security/Steering
22 Not Used
23 Not Used
24 Front Axle, 4WD Indicator Lamp,
TP2 Relay (Gasoline Engine)
A Power Door Lock, Six
-Way Power
Seat, Keyless Entry Module
B Power WindowsUnderhood Fuse/Relay Center
The underhood fuse/relay center is located in the rear of
the engine compartment near the brake fluid reservoir.
Move the retainer clips for the cover to access the
fuse block.
You can remove fuses with a fuse extractor. The fuse
extractor is mounted to the interior fuse block. To
remove fuses if you don't have a fuse extractor, hold the
end of the fuse between your thumb and index finger
and pull straight out.

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6-74
Name Usage
ECM
-B Fuel Pump, PCM/VCM
RR DEFOG Rear Window Defogger
IGN
-E Auxiliary Fan Relay Coil,
A/C Compressor Relay,
Hot Fuel Module, Dual Tanks
HORN Horn, Underhood Lamps
AUX FAN Auxiliary FanName Usage
ECM
-1 Injectors, PCM/VCM, Fuel
Solenoid (Diesel Engine, Fuel
Control Module (Diesel Engine)
HTD ST
-FR Not Used
A/C Air Conditioning
HTD MIR Not Used
ENG
-1 Ignition Switch, EGR, Canister
Purge, EVRV Idle Coast Solenoid,
MAF, Heated O
2,
Fuel Heater (Diesel Engine),
Water Sensor (Diesel Engine),
Boost Solenoid (Diesel Engine),
EPR (Diesel Engine)
HTD ST
-RR Not Used
LIGHTING Headlamp and Panel Dimmer
Switch, Fog and Courtesy Fuses
BATT Battery, Fuse Block Busbar
IGN
-A Ignition Switch
IGN
-B Ignition Switch
ABS Anti
-Lock Brake Module
BLOWER High Blower Relay
STOP/HAZ Stoplamps
HEATED SEATS Not Used

Short Trip/City Scheduled Maintenance -- Gasoline Engines
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7-9
** Drive axle service (see ªRecommended Fluids and
Lubricantsº in the Index for proper lubricant to use):

Check fluid level and add fluid as needed. If driving
in dusty areas or when towing a trailer, drain fluid
and refill every 15,000 miles (25 000 km).

If your vehicle has a locking differential, drain fluid
and refill at first engine oil change.
More frequent lubrication may be required for
heavy
-duty or off-road use.

3500 HD Models with applications requiring
extreme overload/trailer towing conditions and
high
-speed (above 45 mph or 70 km/h) conditions
for extended periods of time must have the drive axle
fluid changed every 30,000 miles (50 000 km).
See ªRecommended Fluids and Lubricantsº in
this section.

Long Trip/Highway Scheduled Maintenance -- Gasoline Engines
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7-30
The services shown in this schedule up to 100,000 miles
(166 000 km) should be performed after 100,000 miles
(166 000 km) at the same intervals. The services shown
at 150,000 miles (240 000 km) should be performed at
the same interval after 150,000 miles (240 000 km).
See ªOwner Checks and Servicesº and ªPeriodic
Maintenance Inspectionsº following.
Footnotes
 The U.S. Environmental Protection Agency or the
California Air Resources Board has determined that the
failure to perform this maintenance item will not nullify
the emission warranty or limit recall liability prior to the
completion of the vehicle's useful life. We, however,
urge that all recommended maintenance services be
performed at the indicated intervals and the maintenance
be recorded.
# Lubricate the front suspension, kingpin bushings,
steering linkage, transmission shift linkage, transfer case
shift linkage, parking brake cable guides, rear drivelinecenter splines, front axle propshaft spline and brake
pedal springs. Ball joints and kingpin bushings should
not be lubricated unless their temperature is 10F
(
-12C) or higher, or they could be damaged.
+ A good time to check your brakes is during tire
rotation. See ªBrake System Inspectionº under ªPeriodic
Maintenance Inspectionsº in Part C of this schedule.
** Drive axle service (see ªRecommended Fluids and
Lubricantsº in the Index for proper lubricant to use):

Check fluid level and add fluid as needed.

If your vehicle has a locking differential, drain fluid
and refill at first engine oil change.

3500 HD Models with applications requiring
high
-speed (above 45 mph or 70 km/h) operation for
extended periods of time must have the drive axle
fluid changed every 30,000 miles (50 000 km).

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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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7-44
Brake-Transmission Shift Interlock (BTSI) Check
(Automatic Transmission)
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. It should be parked on a
level surface.
2. Firmly apply the parking brake (see ªParking Brakeº
in the Index if necessary).
NOTE: Be ready to apply the regular brake
immediately if the vehicle begins to move.
3. With the engine off, turn the key to the RUN
position, but don't start the engine. Without applying
the regular brake, try to move the shift lever out of
PARK (P) with normal effort. If the shift lever
moves out of PARK (P), your vehicle's BTSI
needs service.Ignition Transmission Lock Check
While parked, and with the parking brake set, try to turn
the ignition key to LOCK in each shift lever position.

With an automatic transmission, the key should turn
to LOCK only when the shift lever is in PARK (P).

With a manual transmission, the key should turn to
LOCK only when you press the key release button.
On all vehicles, the key should come out only in LOCK.

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7-49
USAGEFLUID/LUBRICANT
Manual
Transmission
(5
-Speed without
Low Gear, RPO
MG5)
Synchromesh Transmission Fluid
(GM Part No. 12345349
or equivalent).
Automatic
TransmissionDEXRON
-III Automatic
Transmission Fluid.
Key Lock
CylindersMulti-Purpose Lubricant,
Superlube
(GM Part
No. 12346241 or equivalent).
Floor Shift
LinkageLubriplate
Lubricant Aerosol
(GM Part No. 12346293 or
equivalent) or lubricant meeting
requirements of NLGI # 2
Category LB or GC
-LB.
Chassis
LubricationChassis Lubricant (GM Part
No. 12377985 or equivalent) or
lubricant meeting requirements of
NLGI # 2, Category LB or
GC
-LB.
USAGEFLUID/LUBRICANT
Front Wheel
BearingsWheel Bearing Lubricant meeting
requirements of NLGI # 2,
Category GC or GC
-LB (GM Part
No. 1051344 or equivalent).
Front and Rear
Axle (Standard
Differential)SAE 80W-90 Axle Lubricant
(GM Part No. 1052271
or equivalent).
Rear Axle
(Locking
Differential)SAE 80W-90 Axle Lubricant; use
only GM Part No. 1052271. Do
not add friction modifier.
Differential, C3
(HD3500)
Trucks With
Dana Rear AxleSAE 75W-140 Synthetic Axle
Lubricant (GM Part
No. 12346140) or equivalent.
Transfer CaseDEXRON
-III Automatic
Transmission Fluid.
Automatic
Transfer CaseAutomatic Transfer Case Fluid
(GM Part No. 12378396).