1999 GMC C-SERIES AUX

yellowblue
6-70
Name Circuits Protected
HYD BRK Brake Pump Motor Relay
HYD BRK Brake Alarm ModuleName Circuits Protected
B/U IGN3 Fuel Filter Relay, Blower Motor
Relays, ABS Power Relay,
Back
-Up Lamps, Auxiliary Wiring
Relay, IGN 3 Relay, Power
Window Relay, Vehicle Interface
Module, Transmission
Temperature Gage
STOP Stoplamps
WASH/WIPE Windshield Wipers/Washer,
Accessory Relay
DOME/PNL Dome Lamp, Radio Receiver,
Instrument Panel Lights,
A/C Controller,
Headlamp/Seatbelt Module
BLOWER Blower Motor
A/C A/C Clutch Compressor,
A/C Controller
TRN/HAZ Turn Signals, Hazard Flashers
ProCarManuals.com

yellowblue
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
ProCarManuals.com

yellowblue
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.
ProCarManuals.com

yellowblue
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
ProCarManuals.com

yellowblue
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).
ProCarManuals.com

9-yellowblue
9-1
Section 9 Index
A
ir
Brake System Warning Light 2-59 . . . . . . . . . . . . . . . . . . . .
Cleaner 6-17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cleaner Filter 6-77 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Compressor Filter 6-77 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Conditioning 3-5, 6-77 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Conditioning Refrigerants 6-77 . . . . . . . . . . . . . . . . . . . . . .
Dryer 6-34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filter Restriction Indicator 6-17 . . . . . . . . . . . . . . . . . . . . . .
Suspension 2-19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Air Brake Systems 6-33 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Air Dryer 6-34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Alcohol Injector 6-34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Moisture Ejector 6-33 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Alcohol Injector 6-34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Alignment and Balance, Tire 6-51 . . . . . . . . . . . . . . . . . . . . . .
AM-FM Stereo 3-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AM-FM Stereo with Remote Cassette Tape Player 3-10 . . . . .
Antenna 3-12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Antifreeze 6-23 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Anti-Lock
Brakes 4-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Brake System Warning Light 2-61, 4-7 . . . . . . . . . . . . . . . .
Appearance Care 6-59 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Appearance Care Materials 6-66 . . . . . . . . . . . . . . . . . . . . . . . Apply Park Brake Warning Light 2
-60 . . . . . . . . . . . . . . . . . .
Ashtray 2-47 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Audio Systems 3-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Automatic Transmission Fluid 6-18 . . . . . . . . . . . . . . . . . . . . .
Automatic Transmission Shift Indicator Check 7-25 . . . . . . . .
Auxiliary Power Jacks 2-48 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Axle, Rear 6-20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Airshift Control 2-19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Differential Lock Control 2-41 . . . . . . . . . . . . . . . . . . . . . . .
Fluid Capacity 6-76 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Shift Motor 6-20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tw o-Speed Electric Shift Control 2-17 . . . . . . . . . . . . . . . .
Towing 5-15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Battery 6-42 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Battery, Jump Starting 5-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Brake
Adjustment 6
-33 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Air Brake Systems 6-33 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Air Parking Brake 2-26 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electric/Hydraulic Parking Brake 2-25 . . . . . . . . . . . . . . . .
Electric/Hydraulic Parking Brake Fluid 6-36 . . . . . . . . . . . .
Exhaust 2-16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fluid 6-30 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ProCarManuals.com