2004 GMC ENVOY XL trailer

When You Are Ready to Leave After
Parking on a Hill
1. Apply your regular brakes and hold the pedal down
while you:
start your engine,
shift into a gear, and
release the parking brake.
2. Let up on the brake pedal.
3. Drive slowly until the trailer is clear of the chocks.
4. Stop and have someone pick up and store the
chocks.
Maintenance When Trailer Towing
Your vehicle will need service more often when you’re
pulling a trailer. See the Maintenance Schedule for more
on this. Things that are especially important in trailer
operation are automatic transmission uid (don’t overll),
engine oil, axle lubricant, belt(s), cooling system and
brake system. Each of these is covered in this manual,
and the Index will help you nd them quickly. If you’re
trailering, it’s a good idea to review these sections before
you start your trip.
Check periodically to see that all hitch nuts and bolts
are tight.
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Trailer Wiring Harness
Your vehicle may be equipped with the seven-wire trailer
towing harness. This harness has a seven-pin universal
heavy-duty trailer connector that is attached to a bracket
on the hitch platform. The seven-wire harness contains
the following trailer circuits:
Yellow: Left Stop/Turn Signal
Dark Green: Right Stop/Turn Signal
Brown: Running Lamps
White: Ground
Light Green: Back-up Lamps
Red: Battery Feed
Dark Blue: Electric Brakes
If you need to tow a light-duty trailer with a standard
four-way round pin connector, an adapter connector is
available from your dealer.
Your vehicle may also be equipped with wiring for an
electric trailer brake controller. These wires are located
inside the vehicle on the driver’s side under the
instrument panel. These wires should be connected to
an electric trailer brake controller by your dealer or
a qualied service center.
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Automatic Transmission Fluid
When to Check and Change
A good time to check your automatic transmission uid
level is when the engine oil is changed.
Change both the uid and lter every 50,000 miles
(83 000 km) if the vehicle is mainly driven under one or
more of these conditions:
In heavy city traffic where the outside temperature
regularly reaches 90°F (32°C) or higher.
In hilly or mountainous terrain.
When doing frequent trailer towing.
Uses such as found in taxi, police or delivery
service.
If you do not use your vehicle under any of these
conditions, change the uid and lter every
100,000 miles (166 000 km).
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.
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’s 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.
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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.
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 (N) and let the engine idle.
2. Turn on your heater to full hot at the highest fan
speed and open the window as necessary.If you no longer have the overheat warning, you can
drive. Just to be safe, drive slower for about 10 minutes.
If the warning doesn’t come back on, you can drive
normally.
If the warning continues and you have not stopped,
pull over, stop, and park your vehicle right away.
If there’s still no sign of steam, you can push down the
accelerator until the engine speed is about twice as
fast as normal idle speed for at least three minutes while
you’re parked. If you still have the warning,turn off
the engine and get everyone out of the vehicleuntil it
cools down.
You may decide not to lift the hood but to get service
help right away.
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6. Start the engine and let it run until you can feel the
upper radiator hose getting hot. Watch out for the
engine cooling fan.
7. By this time, the coolant level inside the radiator
ller neck may be lower. If the level is lower, add
more of the proper DEX-COOL
®coolant mixture
through the ller neck until the level reaches
the base of the ller neck.8. Then replace the pressure cap. At any time during
this procedure if coolant begins to ow out of the
ller neck, reinstall the pressure cap. Be sure
the pressure cap is hand-tight.
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.
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Fuses Usage
1Electrically-Controlled Air
Suspension
2Passenger’s Side High-Beam
Headlamp
3Passenger’s Side Low-Beam
Headlamp
4 Back-Up-Trailer Lamps
5Driver’s Side High-Beam
Headlamp
6Driver’s Side Low-Beam
Headlamp
7Rear Window Washer,
Headlamp Washer
8 Active Transfer Case
9 Windshield Washer
10 Powertrain Control Module B
11 Fog Lamps
12 Stop Lamp
13 Cigarette LighterFuses Usage
14 Ignition Coils
15 Blank
16 TBC-Ignition 1
17 Crank
18 Air Bag
19 Trailer Electric Brake
20 Cooling Fan
21 Horn
22 Ignition E
23 Electronic Throttle Control
24Instrument Panel Cluster,
Driver Information Center
25Automatic Shift Lock Control
System
26 Backup
27 Engine 1
28 Powertrain Control Module 1
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Fuses Usage
29 Oxygen Sensor
30 Air Conditioning
31 Truck Body Controller
32 Trailer
33 Anti-Lock Brakes (ABS)
34 Ignition A
35 Blower Motor
36 Ignition B
50 Passenger’s Side Trailer Turn
51 Driver’s Side Trailer Turn
52 Hazard Flashers
53 Electric Adjustable Pedal
54 A.I.R. Solenoid
56 A.I.R. PumpRelays Usage
37 Headlamp Washer
38 Rear Window Washer
39 Fog Lamps
40 Horn
41 Fuel Pump
42 Windshield Washer
43 High-Beam Headlamp
44 Air Conditioning
45 Cooling Fan
46 Headlamp Driver Module
47 Starter
49 Electric Adjustable Pedal
55 A.I.R. Solenoid
Miscellaneous Usage
48 Instrument Panel Battery
49 Blank
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Fuses Usage
1Electrically-Controlled Air
Suspension
2Passenger’s Side High-Beam
Headlamp
3Passenger’s Side Low-Beam
Headlamp
4 Back-Up-Trailer Lamps
5Driver’s Side High-Beam
Headlamp
6Driver’s Side Low-Beam
Headlamp
7Rear Window Washer,
Headlamp Washer
8 Active Transfer Case
9 Windshield Washer
10 Powertrain Control Module B
11 Fog Lamps
12 Stop Lamp
13 Cigarette LighterFuses Usage
14 Ignition Coils
15 Canister Vent
16 TBC-Ignition 1
17 Crank
18 Air Bag
19 Trailer Electric Brake
20 Cooling Fan
21 Horn
22 Ignition E
23 Electronic Throttle Control
24Instrument Panel Cluster,
Driver Information Center
25Automatic Shift Lock Control
System
26 Backup
27 Engine 1
28 Powertrain Control Module 1
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