2008 HUMMER H3 trailer

Heavy-Duty Trailer Wiring Package
If your vehicle is equipped with a trailer towing package,
the rear bumper harness will have a seven-pin universal
heavy-duty trailer connector attached to a bracket on the
hitch platform.The trailer towing harness contains the following seven
trailer circuits:
Yellow: Left Stop/Turn Signal
Dark Green: Right Stop/Turn Signal
Brown: Taillamps
White: Ground
Light Green: Back-up Lamps
Red: Battery Feed
Dark Blue: Trailer Brake
If you are charging a remote (non-vehicle) battery, turn
on the headlamps to boost the vehicle system voltage
to properly charge the battery.
4-60

Four-Wire Harness Adapter
If you need to tow a light-duty trailer with a standard
four-way, at pin connector, an adapter is available from
your dealer/retailer.
Use this adapter to
connect a standard
four-way pin connector to
the seven-wire harness
on your vehicle.
Connect the adapter with the tab pointing up. The ip
cap on the vehicle’s seven-wire harness will lock
onto the tab (see arrow in the previous graphic) and
help hold the adapter in place. Plug the four-way
pin connector onto the adapter.
4-61

Trailer Brake Control Wiring Harness
The trailer brake control wiring harness is located
under the instrument panel to the right of the steering
column. The wires are taped to the harness that goes
to the courtesy light under the instrument panel.
The harness will contain the following wires:
Red Wire: AUX B+
Black Wire: Ground
Light Blue Wire: Brake Signal
Dark Blue Wire: Trailer Brakes
Trailer Recommendations
You must subtract your hitch loads from the Cargo
Weight Rating (CWR). CWR is the maximum weight
of the load your vehicle can carry. It doesn’t include the
weight of the people inside, but you can gure about
150 lbs. (68 kg) for each seat. The total cargo load
must not be more than your vehicles CWR.
Weigh your vehicle with your trailer attached, so that
you won’t go over the GVWR or GAWR. If you are using
a weight-distributing hitch, weigh the vehicle without
the spring bars in place.
You’ll get the best performance if you spread out the
weight of your load the right way, and if you choose the
correct hitch and trailer brakes.
For more information seeTowing a Trailer on page 4-50.
4-62

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
parts 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.
To get the right reading, the uid should be at normal
operating temperature, which is 180°F to 200°F
(82°C to 93°C).
Get the vehicle warmed up by driving about
15 miles (24 km) when outside temperatures are above
50°F (10°C). If it is colder than 50°F (10°C), drive
the vehicle in THIRD (3) until the engine temperature
gage moves and then remains steady for 10 minutes.A cold uid check can be made after the vehicle has
been sitting for eight hours or more with the engine off,
but this is used only as a reference. Let the engine
run at idle for ve minutes if outside temperatures are
50°F (10°C) or more. If it is colder than 50°F (10°C), you
may have to idle the engine longer. Should the uid
level be low during this cold check, you must check the
uid hot before adding uid. Checking the uid hot
will give you a more accurate reading of the uid level.
Checking the Fluid Level
Prepare your vehicle as follows:
1. Park your vehicle on a level place. Keep the engine
running.
2. With the parking brake applied, place the shift lever
in PARK (P).
3. With your foot on the brake pedal, move the shift
lever through each gear range, pausing for about
three seconds in each range. Then, position
the shift lever in PARK (P).
4. Let the engine run at idle for three minutes or more.
5-22

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.
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.
If No Steam Is Coming From Your
Engine
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. See “Driving on Grades” under
Towing a Trailer on page 4-50.
If you get the overheat warning with no sign of steam,
try this for a minute or so:
1. In heavy traffic, let the engine idle in NEUTRAL
while stopped. If it is safe to do so, pull off the
road, shift to PARK (P) or NEUTRAL and let the
engine idle.
2. Turn off the air conditioning.
3. Turn on your heater to full hot at the highest fan
speed and open the windows as necessary.
5-30

Engine Fan Noise
This vehicle has 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 clutch is not engaged. This improves fuel
economy and reduces fan noise. Under heavy vehicle
loading, trailer towing and/or high outside temperatures,
the fan speed increases when the clutch 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 disengages.
Power Steering Fluid
SeeEngine Compartment
Overview on page 5-12for
reservoir location.
When to Check Power Steering Fluid
It is not necessary to regularly check power steering uid
unless you suspect there is a leak in the system or
you hear an unusual noise. A uid loss in this system
could indicate a problem. Have the system inspected
and repaired.
How to Check Power Steering Fluid
1. Turn the key off and let the engine compartment
cool down.
2. Wipe the cap and the top of the reservoir clean.
3. Unscrew the cap and wipe the dipstick with a
clean rag.
5-36

Fuse Usage
7 Regulated Voltage Control Power
8 Power Locks
9 Sunroof, Front Washer Pump
10 Accessories (SPO)
11 Air Compressor
12 Transfer Case Control Module
13Radio, Heating, Ventilation, Air
Conditioning Display
14 Body Control Module
15 Rear Wiper Motor
16 Rear Wiper Pump Switch
17 Air Injection Reactor (AIR) Solenoid
18 Spare 6
19 Cluster
20 Rear Turn Signal, Hazard Signal
21 Powertrain Control Module 1
22Mass Air Flow Sensor, Purge
Solenoid
23 Injector
24 Fog Lamp
25 Powertrain Control Module B
26 Transmission Control Module (TCM)
27 Airbags
28 Back-up LampsFuse Usage
29 Antilock Brakes, StabiliTrak®
30 Rear Window Defogger
31 Canister Vent
32 Regulated Voltage Control VSense+
33 Ignition 1
34 Transmission
35 Cruise, Inside Rearview Mirror
36 Horn
37 Driver Side Rear Park Lamp
38 Amplier
39Reduced Intensity Low-Beam
Daytime Running Lamps
40 Passenger Side Headlamp
41 Driver Side Headlamp
42 Trailer Back-Up Lamp
43 Front Park Lamps
44 Air Injection Reactor (AIR) Solenoid
45 Auxiliary Power 2
46 Electronic Throttle Control
47 Oxygen Sensor
48 Air Conditioning Clutch
49 Passenger Side Rear Park Lamp
50 Spare
51 Auxiliary Power 1
5-105

Fuse Usage
52 StabiliTrak®, Antilock Brakes
53 Power Heater Switch
54 Stop
55 Trailer Parking Lamps
56 Front Turn Signal, Hazard Signal
57 Power Sunroof
58Transfer Case Control Module
Switch
59 Climate Control
60 Spare 8
61 Power Seats
62 Air Pump
63 Passenger Side Power Window
64Antilock Brakes, StabiliTrak
®2
Solenoid
67Antilock Brakes, StabiliTrak
®1
Motor
68 Driver Side Power Window
82 Climate Control Fan
83 Electronic Brake Controller
84 Trailer B+ Fuse
85 Starter
91 Megafuse
Relay Usage
66 Fuel Pump
69 Fog Lamp
70 High, Low Beam Headlamps
71 Rear Defogger
72 Windshield Wiper On/Off
73 Windshield Wiper High/Low
74 Horn
75 Headlamp
76 Air Conditioning Clutch
77 Powertrain Control Module
78 Run, Crank
79Reduced Intensity Low-Beam
Daytime Running Lamps
80 Air Injection Reactor (AIR) Solenoid
81 Powertrain (Starter)
86 Spare 2
87 Heating, Ventilation, Air Conditioning
88 Retained Accessory Power
89 Park Lamp
Diode Usage
65 Wiper Diode
90 Air Conditioning Clutch Diode
5-106