1999 GMC C-SERIES lock

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6-55
CAUTION:
Never use oil or grease on studs or nuts. If you
do, the nuts might come loose. Your wheel could
fall off, causing a serious accident.
Hub-Piloted Wheels, 8-Hole or 10-Hole
The studs and nuts used with these wheels have
right
-hand threads.
1. With intermittent pilot pads, position a pad at
12 o'clock to center the wheel and reduce run
-out.
2. Put the tire and rim assembly on the axle hub. Install
the outer rear tire and rim assembly so that its valve
stem is exactly opposite the valve stem on the inner
tire and rim assembly.
3. Put on the wheel nuts.
4. Finger
-tighten the nuts.
5. Oil the surfaces between
the nuts and washers as
shown. Do not oil the
studs or the threads of
the nut.
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6-68
Electrical System
Add-On Electrical Equipment
NOTICE:
Don't add anything electrical to your vehicle
unless you check with your dealer first. Some
electrical equipment can damage your vehicle
and the damage wouldn't be covered by your
warranty. Some add
-on electrical equipment can
keep other components from working as
they should.
Headlamp Wiring
The headlamp wiring is protected by a circuit breaker in
the light switch. An electrical overload will cause the
lights to go on and off, or in some cases to remain off.
If this happens, have your headlamp wiring checked
right away.
Windshield Wiper Fuses
The windshield wiper motor is protected by a circuit
breaker inside the motor and a circuit breaker in the fuse
block. If the motor overheats, the wipers will stop until
the motor cools. If the overload is caused by an
electrical problem, be sure to get it fixed.
Fusible Links
A fusible link is a short piece of wire several gage sizes
smaller than the circuit it protects. It will melt in an
overload situation, opening the circuit.
Your starter relay and other circuits have these fusible
links. The size is printed on the insulation. If the insulation
is burned beyond recognition, consult your GM dealer for
the proper size. Replace a fusible link with one of the
same size and insulation type. Fusible link insulation is a
special purpose high
-temperature material.
The hydraulic brake booster motor feed circuit and
starter relay circuit are protected by a fusible link.
Vehicles with a diesel engine have a fusible link for the
intake heater feed circuit. Vehicles equipped with an
electronically controlled diesel engine also have a
fusible link for the engine control unit.
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6-69 Power Windows and Other Power Options
Circuit breakers in the fuse panel protect the power
windows and other power accessories. When the current
load is too heavy, the circuit breaker opens and closes.
This protects the circuit until the current load returns to
normal or the problem is fixed.
Fuses and Circuit Breakers
The wiring circuits in your vehicle are protected from
short circuits by a combination of fuses, circuit breakers,
maxi
-fuses and fusible links. This greatly reduces the
chance of a fire caused by an electrical problem. There
may be a fuse taped to the wiring harness inside the
battery box and one near the generator also taped to the
wiring harness.
There are two circuit breaker/fuse blocks in your
vehicle: the instrument panel circuit breaker block and
the maxi
-fuse block.
Instrument Panel Circuit Breaker Block
This fuse block is in the lower portion of the instrument
panel, to the left of the steering column.
To open the door, pull up
and outward on the recessed
door handle and the door
will snap out.
To install the door, place the lower door into the bottom
retainer and push the top of the door in until it snaps
into place.
If you ever have a problem on the road and don't have a
spare circuit breaker, you can borrow one of the correct
value. Just pick some feature of your vehicle that you
can get along without
-- like the radio or cigarette
lighter
-- and use its circuit breaker if it is of the value
you need. Remember to replace the circuit breaker as
soon as you can.
These circuit breakers are non
-cycling; do not replace
them with cycling circuit breakers. Also, don't use
circuit breakers of higher amperage than those indicated
on the circuit breaker block.
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6-71
Name Circuits Protected
CHAS Exhaust Brake, Air Suspension
Dump Valve, Air Dryer, HYD
ABS ECHU
PARK LP Auxiliary Wiring, Air Conditioner
Controls, Parking Lamps, Turn
Signals, Taillamps, Stoplamps,
Marker Lamps, Trailer Running
Lamps, Lighted Mirrors, Radio
Receiver, Mirror Clearance Lamps
HORN Horn/Diagnostic Connector
PRK BRK Parking Brake Module
FUEL Heated Fuel Filter (Diesel
Engines) or Fuel Pump
(Gasoline Engines)
AXLE Heated Mirrors, Radiator Shutters,
Tw o
-Speed Axle Motor,
Tw o
-Speed Axle Switch
MRKR LP Roof Marker Lamps,
Trailer Marker Lamps,
Marker Lamp RelayName Circuits Protected
CIG/AUX Cigarette Lighter,
Auxiliary Power Jacks
AUX Auxiliary Wiring Relay
IGN RLY/VIN Vehicle Interface Module
(Diesel Engines) or Generator,
Coil, Injectors (Gasoline Engines)
WDO Power Windows
CRNK Starter Relay
IGN SW Instrument Panel Cluster Telltales
AUX Auxiliary Wiring
RDO Radio, Auxiliary Wiring
DR LK Power Door Locks
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6-72
Maxi-Fuse Block
When a circuit goes out, first check the instrument panel
circuit breaker block. If no circuit breakers are out there,
the problem could in the maxi
-fuse block.
This block uses blade
-type fuses. It's on the upper
passenger side of the engine compartment at the rear.
To access the maxi-fuse block, gently squeeze both
sides of the cover to unlatch the tabs at the top. Then,
unsnap both attachments at the bottom and remove
the cover.
Power is fed through these fuses to devices such as the
headlamp switch, ignition switch feed circuits and the
auxiliary brake pump (hydraulic brake vehicles).
Be sure to replace maxi
-fuses with maxi-fuses of the
same rating. Do not use maxi
-fuses of higher amperage
than those indicated on the maxi
-fuse block.
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6-73
Name Circuits/Circuit Breakers
Protected
STP/HAZ
TURNStop Lamp, Turn Signal/Hazard
Lights, Fuel, Ignition Relay
(Gasoline Engines)
IGN SW3 Air Conditioner, Ignition Switch,
Axle, ChassisName Circuits/Circuit Breakers
Protected
INT/EXT
LIGHTSParking Lamps,
Dome/Panel Lights
HEAD LAMP Headlamps,
Daytime Running Lamps
AUX WRG Auxiliary, Park Brake
IGN SW1 Ignition Switch, Wash/Wipe,
Crank, Radio
HYD PUMP Hydraulic Brake,
Brake Pump Motor
HYD ABS EHCU
PWR
WDO/LCKSWindow, Door Locks
PARK BRK Parking Brake Motor
BLOWER
HORNBlower, Horn, Cigarette
Lighter/Auxiliary
FUEL/ENGINE Empty
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7-24 At Least Twice a Year
Restraint System Check
Make sure the safety belt reminder light (if equipped)
and all your belts, buckles, latch plates, retractors and
anchorages are working properly. Look for any other
loose or damaged safety belt system parts. If you see
anything that might keep a safety belt system from
doing its job, have it repaired. Have any torn or frayed
safety belts replaced.
Wiper Blade Check
Inspect wiper blades for wear or cracking. Replace blade
inserts that appear worn or damaged or that streak or
miss areas of the windshield. Also see ªWiper Blades,
Cleaningº in the Index.
Weatherstrip Lubrication
Silicone grease on weatherstrips will make them last
longer, seal better, and not stick or squeak. Apply
silicone grease with a clean cloth. During very cold,
damp weather more frequent application may be
required. (See ªRecommended Fluids and Lubricantsº
in the Index.)Body Lubrication Service
Lubricate all surfaces such as door checks, door lock
bolts, lock strike plates, door hinge bushings and
dovetail bumper wedges. Where oil holes are provided,
a dripless oil can be used. The seat adjusters, seat track,
door weatherstrips and rubber hood bumpers should also
be lubricated.
Part C tells you what to use. More frequent lubrication may
be required when exposed to a corrosive environment.
Parking Brake Check
Park on a fairly steep hill and hold the vehicle with the
parking brake only. This checks holding ability.
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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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