2000 GMC ENVOY engine

4-56 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 fluid (don't
overfill), engine oil, axle lubricant, belt, cooling system
and brake system. Each of these is covered in this
manual, and the Index will help you find 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.
Trailer Wiring Harness
The heavy-duty trailer wiring is an eight-wire harness
assembly. The harness is stored under the vehicle, on the
driver's side corner frame rear crossmember. The harness is
fused in the engine compartment fuse block. See ªFuses and
Circuit Breakersº in the Index. The harness does not have a
connector and should be wired by a qualified electrical
technician. The technician can use the following color code
chart when connecting the wiring harness to your trailer.

Dark Blue: Use for electric trailer brakes or
auxiliary wiring.

Red: Use for battery charging; it connects to the
starter solenoid.

Light Green: Back
-up lamps.

Brown: Taillamps and parking lamps.

Yellow: Left stoplamp and turn signal.

Dark Green: Right stoplamp and turn signal.

White: Ground wire.

Light Blue: Auxiliary stoplamp.
Securely attach the harness to the trailer, then tape or
strap it to your vehicle's frame rail. Be sure you leave it
loose enough so the wiring doesn't bend or break, but
not so loose that it drags on the ground. Store the
harness in its original place. Wrap the harness together
and tie it neatly so it won't be damaged.
ProCarManuals.com

5-
5-1
Section 5 Problems on the Road
Here you'll find what to do about some problems that can occur on the road.
5
-2 Hazard Warning Flashers
5
-3 Other Warning Devices
5
-3 Jump Starting
5
-7 Towing Your Vehicle
5
-8 Engine Overheating5
-11 Cooling System
5
-19 Engine Fan Noise
5
-19 If a Tire Goes Flat
5
-20 Changing a Flat Tire
5
-30 If You're Stuck: In Sand, Mud, Ice or Snow
ProCarManuals.com

5-5
5. Check that the jumper cables don't have loose or
missing insulation. If they do, you could get a shock.
The vehicles could be damaged too.
Before you connect the cables, here are some basic
things you should know. Positive (+) will go to
positive (+) and negative (
-) will go to a heavy,
unpainted metal engine part. Don't connect
positive (+) to negative (
-) or you'll get a short that
would damage the battery and maybe other parts too.
6. Connect the red
positive (+) cable to the
positive (+) terminal of
the vehicle with the
dead battery.
7. Don't let the other end
touch metal. Connect it
to the positive (+)
terminal of the
good battery.
8. Now connect the black
negative (
-) cable to
the good battery's
negative (
-) terminal.
ProCarManuals.com

5-6
Don't let the other end touch anything until the next
step. The other end of the negative cable doesn't go
to the dead battery. It goes to a heavy unpainted
metal part on the engine of the vehicle with the
dead battery.
9. Attach the cable at least
18 inches (45 cm) away
from the dead battery,
but not near engine parts
that move. The electrical
connection is just as
good there, but the
chance of sparks getting
back to the battery is
much less.10. Now start the vehicle with the good battery and
run the engine for awhile.
11. Try to start the vehicle with the dead battery.
If it won't start after a few tries, make sure all
connections are good. If it still won't start,
it probably needs service.
CAUTION:
Fans or other moving engine parts can injure you
badly. Keep your hands away from moving parts
once the engine is running.
12. Remove the cables in reverse order to prevent
electrical shorting. Take care that they don't touch
each other or any other metal.
ProCarManuals.com

5-7
Removal Procedure
A. Heavy Unpainted, Metal Engine Part
B. Good Battery
C. Dead Battery
Towing Your Vehicle
CAUTION:
To help avoid serious personal injury to you
or others:

Never let passengers ride in a vehicle that is
being towed.

Never tow faster than safe or posted speeds.

Never tow with damaged parts not
fully secured.

Never get under your vehicle after it has
been lifted by the tow truck.

Always secure the vehicle on each side with
separate safety chains when towing it.

Use only the correct hooks.
ProCarManuals.com

5-8
NOTICE:
Use the proper towing equipment to avoid
damage to the bumper, fascia or fog lamp areas
of the vehicle.
With current trends in automotive styles and design,
it is essential that the correct towing equipment is used
to tow a vehicle. Your vehicle can be towed with with
wheel lift or car carrier equipment. When towing with
wheel lift equipment, the transfer case must be in
NEUTRAL and the following tow limits must be used:

Towing from the front
-- 55 mph (88 km/h) or
legal speed limit and distance is unlimited

Towing from the rear
-- 35 mph (55 km/h),
50 miles (80 km)
NOTICE:
If the towing limits must be exceeded, a towing
dolly must be used under the front wheels or
vehicle/powertrain damage will occur.
Consult your dealer or a professional towing service if
you need to have your vehicle towed. See ªRoadside
Assistanceº in the Index.
Engine Overheating
You will find a coolant temperature gage on your
vehicle's instrument panel. See ªGagesº in the Index.
ProCarManuals.com

5-9 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 fire. 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 fire because you keep
driving with no coolant, your vehicle can be
badly damaged. The costly repairs would not
be covered by your warranty.
ProCarManuals.com

5-10 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 ªDriving on Gradesº in the Index.
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 window as necessary.
3. If you're 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 doesn't come back on, you can
drive normally.
If the warning continues, pull over, stop, and park
your vehicle right away.
If there's still no sign of steam, 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 vehicle until it
cools down.
You may decide not to lift the hood but to get service
help right away.
ProCarManuals.com