
Relay Usage
ECU/PTO*Engine Control Unit/Power Take-Off
*Diesel 7.8 DURAMAX
®
BRK LAMPC4/C5 Brake Lamps,
C6/C7/C8 Tractor/Trailer Wiring
DRL Daytime Running Lamps
IGN-4 Ignition
CHMSL Center High Mounted Stoplamp
MRK LTS Sidemarker and Clearance Lamps
HTD/MIRR Heated Mirrors
HTR Diesel Heated Fuel
RT TRN TRLR Passenger’s Side Trailer Turn Signal
Blank Not Used
LT TRN TRLR Driver’s Side Trailer Turn Signal
Blank Not Used
Blank Not Used
Blank Not Used
Underhood Fuse Block
When a circuit goes out, the problem could be in
either the primary or secondary underhood
fuse blocks. These blocks use blade-type fuses.
Both underhood fuse blocks are located in
the engine compartment, on the passenger’s side
of the vehicle.
To access the fuse blocks, 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.
Be sure to replace fuses with fuses of the same
rating. Do not use fuses of higher amperage
than those indicated on the fuse block.
344

Fuse Usage
NOTE 3L18 Fuel, LG4 Powertrain Control
Valve, LG5 Electronic Control
Module
STUD A Spare
STUD B Spare
Relay Usage
NOTE 1LLY/L18 Fuel Pump Relay, LG4/LG5
Heated Fuel Relay
IGN B Ignition Relay
STARTER Starter Relay
HORN Horn Relay
IGN A Ignition Relay
PTO/ECU*Power Take-Off/Engine Control Unit
(*Diesel 7.8L LG4)
REVERSE Reverse Relay
NEUTRAL
STARTNeutral Start (LG4 Allison Automatic
Transmission Series 3000/3500)
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 Climate Control System
NOTEC4/C5 Electric Brake,
C6/C7/C8 Brake Lamps Secondary Underhood
Fuse Block
346

(11)= Chassis Lubrication Service: Lubricate all
grease fittings in front suspension, front axle,
and steering linkage. DO NOT lubricate kingpin
bushings with air pressure equipment; instead,
use a hand grease gun to ensure complete purge
and eliminate sealer cap distortion. Front axle
tie rod ends, both upper and lower kingpin fittings,
and both steering linkage relay rod ends should
be greased with the vehicle loaded on the ground
and wheels turned straight ahead, NOT with
the vehicle on a hoist. Apply kingpin bushing
lubricant to both upper and lower kingpin grease
fittings until new lubricant purges from between
the upper shim pack and thrust bearing. Lubricate
transmission and shift linkage, hood latches
and hood hinges, parking brake lever pivot, clevis
pins and linkage, disc brake caliper rails, clutch
linkage and release bearing (if equipped), bearing
pads, propshaft universal joints, brake camshaft
bracket, slack adjusters, pedal shaft, clutch
cross shaft, clutch pedal springs, and clutch cable
bushing at transmission. Lubricate suspension,
axle, and steering linkage more often when
operating under dusty or muddy conditions and in
excessive off-road use. Frequently power-washed
vehicles will require more frequent lubrication.(12)= Check steering system:
•Look for damaged, loose, or missing parts.
Inspect the steering linkage relay rod and
tie rod ends for looseness or lack of lubricant.
Also look for parts showing signs of wear
or lack of lubrication. Replace parts as
needed. Also check steering gear mounting
bolts, pitman arm nut, gear housing upper
cover and side cover attaching bolts, steering
column mounting bolts and cardan joint
clamp bolts; tighten if necessary. See the
service manual.
•Inspect power steering hoses, tubes, and
fittings for leaks. Hoses and lines must not
be twisted, kinked, or tightly bent. Make sure
clips, clamps, supporting tubes, and hoses
are in place and properly secured.
•Check steering gear for leakage around
pitman shaft and housing. If leakage is evident
(lubricant oozing out, not just oily film), leak
should be corrected immediately.
386

Care of
Safety Belts............................................. 334
Your Cassette Tape Player....................... 202
Your CD Player........................................ 204
Your CDs ................................................. 203
Center Console Storage Area...................... 135
Center Passenger Position, Safety Belts........ 37
Charging System Light................................ 167
Check
Engine Light............................................ 174
Gages Warning Light............................... 180
Checking Things Under the Hood................ 266
Chemical Paint Spotting.............................. 338
Child Restraints
Child Restraint Systems............................. 49
Infants and Young Children........................ 45
Lower Anchors and Tethers for Children..... 57
Older Children........................................... 42
Securing a Child Restraint in a Rear
Outside Seat Position............................. 58
Securing a Child Restraint in the Center
Rear Seat Position (Crew Cab) or
Center Front Position.............................. 60
Securing a Child Restraint in the Right
Front Seat Position................................. 63
Where to Put the Restraint................. 54, 55
Chime Level Adjustment.............................. 204Cigarette Lighter.......................................... 157
Cleaning
Aluminum or Chrome-Plated Wheels........ 337
Exterior Lamps/Lenses............................. 335
Fabric/Carpet........................................... 333
Finish Care.............................................. 335
Inside of Your Vehicle .............................. 331
Instrument Panel, Vinyl, and Other
Plastic Surfaces.................................... 334
Tires........................................................ 337
Underbody Maintenance........................... 338
Washing Your Vehicle .............................. 335
Weatherstrips........................................... 334
Windshield and Wiper Blades................... 336
Climate Control System............................... 157
Outlet Adjustment..................................... 160
Rear Heating System............................... 161
Collision Damage Repair............................. 410
Control of a Vehicle..................................... 210
Coolant
Engine Temperature Gage........................ 173
Heater, Engine......................................... 111
Low Warning Light................................... 173
Surge Tank Pressure Cap........................ 288
Cooling System........................................... 290
Cruise Control............................................. 146
419

Seats
Air Suspension Seats................................. 13
Bucket Seats............................................... 9
Rear Seat Operation.................................. 20
Split Bench Seat........................................ 13
Securing a Child Restraint
Center Rear Seat Position (Crew Cab) or
Center Front Position.............................. 60
Rear Outside Seat Position........................ 58
Right Front Seat Position........................... 63
Service........................................................ 248
California Proposition 65 Warning............. 248
Doing Your Own Work............................. 249
Engine Fan Breakage.............................. 250
Engine Soon Light................................... 174
Publications Ordering Information............. 415
Transmission Warning Light..................... 168
Servicing Your Airbag-Equipped Vehicle......... 80
Setting the Time.......................................... 185
Sheet Metal Damage................................... 337
Shoulder Belt Height Adjuster........................ 35
Signals, Turn and Lane-Change.................. 144
Sliding Rear Windows................................... 94
Snow Plow.................................................. 240
Specifications, Capacities............................ 347
Speedometer............................................... 163Split Bench Seat........................................... 13
Starting Your Diesel Engine ......................... 100
Starting Your Gasoline Engine....................... 97
Steering...................................................... 217
Steering Wheel, Tilt Wheel.......................... 142
Storage Areas............................................. 135
Center Console Storage Area................... 135
Stuck in Sand, Mud, Ice, or Snow............... 236
Sun Visors.................................................... 95
Suspension, Air........................................... 129
Switchbanks, Instrument Panel.................... 154
T
Tachometer................................................. 163
Theft-Deterrent, Radio................................. 201
Tilt Wheel.................................................... 142
Tires........................................................... 321
Aluminum or Chrome-Plated Wheels,
Cleaning............................................... 337
Cleaning.................................................. 337
Dual Tire Operation.................................. 323
If a Tire Goes Flat................................... 330
Inflation - Tire Pressure............................ 322
Tightening the Wheel Nuts....................... 325
Wheel Alignment and Tire Balance........... 324
428