2005 GMC SIERRA trailer

How to Check
Because this operation can be a little difficult, you may
choose to have this done at the dealership service
department.
If you do it yourself, be sure to follow all the instructions
here, or you could get a false reading on the dipstick.
Notice:Too much or too little uid can damage
your transmission. Too much can mean that some
of the uid could come out and fall on hot engine
part or exhaust system parts, starting a re.
Too little uid could cause the transmission to
overheat. Be sure to get an accurate reading if you
check your transmission uid.
Wait at least 30 minutes before checking the
transmission uid level if you have been driving:
When outside temperatures are above 90°F (32°C).
At high speed for quite a while.
In heavy traffic — especially in hot weather.
While pulling a trailer.
Checking the Fluid Level
Prepare your vehicle as follows:
Park your vehicle on a level place. Keep the
engine running.
With the parking brake applied, place the shift lever
in PARK (P).
With your foot on the brake pedal, run the engine
for at least once minute and shift to DRIVE (D).
Then shift to NEUTRAL (N) and then REVERSE (R)
to ll the hydraulic system. Then, position the
shift lever in PARK (P).
Allow the engine to run at idle (500–800 rpm).
Slowly release the brake pedal.
Then, without shutting off the engine, follow these steps:
Cold Check Procedure
The purpose of the cold check is to determine if the
transmission has enough uid to be operated safely until
a hot check can be made. The uid level rises as uid
temperature increases. DO NOT ll above the COLD
CHECK band if the transmission uid is below normal
operating temperatures.
1. Pull out the dipstick and wipe it with a clean rag or
paper towel.
2. Push it back in all the way, wait three seconds and
then pull it back out again.
5-31

If Steam Is Coming From Your Engine
{CAUTION:
Steam from an overheated engine can burn
you badly, even if you just open the hood. Stay
away from the engine if you see or hear steam
coming from it. Just turn it off and get
everyone away from the vehicle until it cools
down. Wait until there is no sign of steam or
coolant before you open the hood.
If you keep driving when your engine is
overheated, the liquids in it can catch re. You
or others could be badly burned. Stop your
engine if it overheats, and get out of the
vehicle until the engine is cool.
SeeOverheated Engine Protection Operating
Mode (V8 Engines Only) on page 5-39for
information on driving to a safe place in an
emergency.Notice:If your engine catches re because you
keep driving with no coolant, your vehicle can
be badly damaged. The costly repairs would not be
covered by your warranty. SeeOverheated Engine
Protection Operating Mode (V8 Engines Only)
on page 5-39for information on driving to a safe
place in an emergency.
If No Steam Is Coming From
Your Engine
An overheat warning, along with a low coolant condition,
can indicate a serious problem.
If you get an engine overheat warning but see or hear
no steam, the problem may not be too serious.
Sometimes the engine can get a little too hot when you:
Climb a long hill on a hot day.
Stop after high-speed driving.
Idle for long periods in traffic.
Tow a trailer. SeeTowing a Trailer on page 4-68.
5-38

If you get the overheat warning with no sign of steam,
try this for a minute or so:
1. If your air conditioner is on, turn it off.
2. Turn on your heater to full hot at the highest fan
speed and open the windows as necessary.
3. If you are in a traffic jam, shift to NEUTRAL (N);
otherwise, shift to the highest gear while
driving — DRIVE (D) or THIRD (3).
If you no longer have the overheat warning, you can
drive. Just to be safe, drive slower for about 10 minutes.
If the warning does not come back on, you can drive
normally.
If the warning continues, pull over, stop, and park your
vehicle right away.
If there is still no sign of steam and your vehicle is
equipped with an engine-driven cooling fan, push down
the accelerator until the engine speed is about twice
as fast as normal idle speed for at least three minutes
while you are parked.
If there is still no sign of steam and your vehicle is
equipped with an electric engine cooling fan, idle the
engine for three minutes while you are parked.If you still have the warning,turn off the engine and get
everyone out of the vehicleuntil it cools down. Also,
see “Overheated Engine Protection Operating Mode”
later in this section.
You may decide not to lift the hood but to get service
help right away.
Overheated Engine Protection
Operating Mode (V8 Engines Only)
If an overheated engine condition exists and the
REDUCED ENGINE POWER message is displayed, an
overheat protection mode which alternates ring
groups of cylinders helps prevent engine damage. In
this mode, you will notice a loss in power and engine
performance. This operating mode allows your vehicle to
be driven to a safe place in an emergency. Driving
extended miles (km) and/or towing a trailer in the
overheat protection mode should be avoided.
Notice:After driving in the overheated engine
protection operating mode, to avoid engine damage,
allow the engine to cool before attempting any repair.
The engine oil will be severely degraded. Repair the
cause of coolant loss, change the oil and reset the oil
life system. SeeEngine Oil (Gasoline Engine) on
page 5-20.
5-39

Engine Fan Noise
If your vehicle is equipped with a clutched engine
cooling fan, when the clutch is engaged, the fan spins
faster to provide more air to cool the engine. In
most everyday driving conditions, the fan is spinning
slower and the clutch is not fully engaged. This improves
fuel economy and reduces fan noise. Under heavy
vehicle loading, trailer towing, and/or high outside
temperatures, the fan speed increases as the clutch
more fully engages, so you may hear an increase in fan
noise. This is normal and should not be mistaken as
the transmission slipping or making extra shifts.
It is merely the cooling system functioning properly.
The fan will slow down when additional cooling is not
required and the clutch disengages.You may also hear this fan noise when you start the
engine. It will go away as the fan clutch partially
disengages.
If your vehicle is equipped with electric cooling fans, you
may hear the fans spinning at low speed during most
everyday driving. The fans may turn off if no cooling is
required. Under heavy vehicle loading, trailer towing,
and/or high outside temperatures, or if you are operating
your air conditioning system, the fans change to high
speed and you may hear an increase in fan noise.
This is normal and indicates that the cooling system is
functioning properly. The fans will change to low
speed when additional cooling is no longer required.
5-45

Operating your vehicle with a light load means:
The total weight of occupants in your vehicle is less
than the total seating capacity number your vehicle
was designed to carry multiplied by 150 lbs (68 kg).
The total seating capacity number is on the Tire
and Loading Information label.
No more than 200 lbs (91 kg) of cargo, which must
be secured in the cargo area.
No trailer is attached to your vehicle.
You have not added any additional equipment to
your vehicle, like a truck cap or tool box.
The vehicle load capacity and the rear axle load
capacity are reduced when the tire pressure is lowered
to the amount recommended for improved ride.
Before operating your vehicle with passengers or cargo
greater than a light-load, you must inate the rear
tires to the recommended cold tire pressure shown on
the Tire and Loading Information Label. SeeLoading
Your Vehicle on page 4-50.
Dual Tire Operation
When the vehicle is new, or whenever a wheel, wheel
bolt or wheel nut is replaced, check the wheel nut torque
after 100, 1,000 and 6,000 miles (160, 1 600 and
10 000 km) of driving. For proper torque and wheel nut
tightening information, seeRemoving the Spare Tire
and Tools on page 5-93.
The outer tire on a dual wheel setup generally wears
faster than the inner tire. Your tires will wear more
evenly and last longer if you rotate the tires periodically,
seeTire Inspection and Rotation on page 5-83. Also
seeScheduled Maintenance on page 6-4.
{CAUTION:
If you operate your vehicle with a tire that is
badly underinated, the tire can overheat. An
overheated tire can lose air suddenly or catch
re. You or others could be injured. Be sure all
tires (including the spare) are properly inated.
SeeInation - Tire Pressure on page 5-79, for
information on proper tire ination.
5-82

Fuses Usage
RR WPR Not Used
SEO ACCYSpecial Equipment Option
Accessory
WS WPR Windshield Wipers
TBC ACCYTruck Body Controller
Accessory
IGN 3 Ignition, Heated Seats
Fuses Usage
4WDFour-Wheel Drive System,
Auxiliary Battery
HTR A/C Climate Control System
LOCK (Relay)Power Door Lock Relay
(Lock Function)
HVAC 1 Climate Control System
L DOORDriver’s Door Harness
Connection
CRUISECruise Control, Power Take
Off (PTO)
UNLOCK (Relay)Power Door Lock Relay
(Unlock Function)
RR FOG LP Not Used
BRAKE Anti-Lock Brake System
DRIVER UNLOCKPower Door Lock Relay
(Driver’s Door Unlock
Function)
IGN 0 TCM
TBC IGN 0 Truck Body Controller
VEH CHMSLVehicle and Trailer High
Mounted Stoplamp
LT TRLR ST/TRN Left Turn Signal/Stop Trailer
LT TRNLeft Turn Signals and
Sidemarkers
5-123

Fuses Usage
VEH STOPVehicle Stoplamps, Brake
Module, Electronic Throttle
Control Module
RT TRLR ST/TRN Right Turn Signal/Stop Trailer
RT TRNRight Turn Signals and
Sidemarkers
BODY Harness Connector
DDM Driver Door Module
AUX PWR 2 Not Used
LOCKS Power Door Lock System
ECC Not Used
TBC 2C Truck Body Controller
FLASH Flasher Module
CB LT DOORSLeft Power Windows Circuit
Breaker
TBC 2B Truck Body Controller
TBC 2A Truck Body ControllerCenter Instrument Panel Fuse Block
The center instrument panel utility block is located
underneath the instrument panel, to the left of the
steering column.
Device Usage
SEO Special Equipment Option
TRAILER Trailer Brake Wiring
UPFIT Uptter (Not Used)
SL RIDERide Control Harness
Connection
HDLR 2 Headliner Wiring Connector
BODY Body Wiring Connector
5-124

*1— Gasoline Engine and Diesel Engine.
*2— Gasoline Engine; ECMRPV — Diesel Engine.
*3— Gasoline Engine; FUEL HT — Diesel Engine.
*4— Gasoline Engine; ECM I — Diesel Engine.
*5— IGN/EDU
Fuses Usage
GLOW PLUGDiesel Glow Plugs and Intake
Air Heater
CUST FEED Gasoline Accessory Power
HYBRID Hybrid
STUD #1Auxiliary Power (Single
Battery and Diesels Only)/
Dual Battery (TP2) Do not
install fuse.
MBECMid Bussed Electrical Center
Power Feed, Front Seats,
Right Doors
BLOWER Front Climate Control Fan
LBECLeft Bussed Electrical Center,
Door Modules, Door Locks,
Auxiliary Power Outlet—Rear
Cargo Area and Instrument
Panel
STUD 2Accessory Power/Trailer
Wiring Brake Feed
Fuses Usage
ABS Anti-Lock Brakes
VSES/ECAS Vehicle Stability
IGN A Ignition Power
IGN B Ignition Power
LBEC 1Left Bussed Electrical Center,
Left Doors, Truck Body
Controller, Flasher Module
TRL PARK Parking Lamps Trailer Wiring
RR PARKRight Rear Parking and
Sidemarker Lamps
LR PARKLeft Rear Parking and
Sidemarker Lamps
PARK LP Parking Lamps Relay
STRTR Starter Relay
INTPARK Interior Lamps
STOP LP Stoplamps
TBC BATTTruck Body Controller Battery
Feed
S/ROOF Sunroof
SEO B2 Off-Road Lamps
4WSVent Solenoid
Canister/Quadrasteer Module
Power
RR HVAC Not Used
5-127