1999 GMC JIMMY ECU

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4-56 Trailer Wiring Harness
The light-duty trailer wiring is a six-wire harness
assembly. The optional heavy
-duty trailer wiring is an
eight
-wire harness assembly. The harnesses are stored
under the vehicle, along the passenger
-side frame
crossmember on two
-door vehicles or on the driver's
side corner frame rear crossmember on four
-door
vehicles. The heavy
-duty trailer wiring has a 30-amp
feed wire with an inline fuse located by the junction
block. See ªFuses and Circuit Breakersº in the Index.
Both harnesses have no 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 (eight
-wire harness only).
Light Green: Back
-up lamps
(eight
-wire harness only).

Brown: Taillamps and parking lamps.

Yellow: Left stoplamp and turn signal.

Dark Green: Right stoplamp and turn signal.

White (Heavy Gauge): Ground wire.

White (Light Gauge): 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.

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5-7
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.
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 wheel lift or car
carrier equipment. If your vehicle has a manual transmission,
you must use a towing dolly under the rear wheels when
towing from the front with wheel lift equipment.
Tw o
-wheel-drive vehicles must abide by the following tow
limits when being towed by wheel lift equipment:

Towing from the front
-- 35 mph (55 km/h),
50 miles (80 km)

Towing from the rear
-- 35 mph (55 km/h),
50 miles (80 km)

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5-29
Follow this diagram to store the
underbody
-mounted spare.
A. Retainer
B. Valve Stem
(Pointed Down)
C. Spare or Flat Tire
D. Spring
E. Wheel Wrench
F. Lower
G. Raise
H. Hoist Arm1. Put the tire on the ground at the rear of the vehicle,
with the valve stem pointed down and to the rear.
2. Pull the retainer through the wheel.
3. Put the chisel end of the wheel wrench, on an angle,
through the hole in the rear bumper and into the hoist
shaft. Turn the wheel wrench clockwise until the tire
is raised against the underside of the vehicle.
You will hear two ªclicksº when the tire is secure,
but pull on the tire to make sure.

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5-31
Reinstall the locking wheel nut using the wheel wrench.
Then push the lock case onto the lug nut until it stops.
The key does not have to be inserted into the lock. Push
the lock case to be sure it is secured. The special lug nut
and lock case is not intended to be used on any road
wheel, only on the spare wheel carrier. Tighten the nuts
on the wheel carrier to 22 to 32 lb
-ft (30 to 40 N´m).
CAUTION:
Make sure the tire and carrier are secure.
Driving with the tire or carrier unlatched could
injure pedestrians or damage the vehicle.
Return the jack, wheel wrench and wheel blocks to the
proper location in your vehicle's rear area. Secure the
items and replace the jack cover.
A. Retainer
B. Rubber Band (Some Models)
C. Work Gloves
D. Mat
E. Jack Storage Cover
F. Wheel Blocks
G. Hub Cap Removal Tool (Some Models)
H. Wheel Wrench
I. Jack
J. Jacking Instructions

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6-14
Remote Oil Filter (Four-Wheel Drive)
The access door for the
remote oil filter is in the
steering linkage shield
assembly located under
the radiator support. Twist
the screw to unlock or lock
the door. If you open the
door, make sure it is
securely closed when
you are finished.
What to Do with Used Oil
Did you know that used engine oil contains certain
elements that may be unhealthy for your skin and could
even cause cancer? Don't let used oil stay on your skin
for very long. Clean your skin and nails with soap and
water, or a good hand cleaner. Wash or properly throw
away clothing or rags containing used engine oil. (See
the manufacturer's warnings about the use and disposal
of oil products.)
Used oil can be a real threat to the environment. If you
change your own oil, be sure to drain all free
-flowing oil
from the filter before disposal. Don't ever dispose of oil by
putting it in the trash, pouring it on the ground, into
sewers, or into streams or bodies of water. Instead, recycle
it by taking it to a place that collects used oil. If you have
a problem properly disposing of your used oil, ask your
dealer, a service station or a local recycling center for help.

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6-49
NOTICE: (Continued)
Use another type of traction device only if its
manufacturer recommends it for use on your
vehicle and tire size combination and road
conditions. Follow that manufacturer's instructions.
To help avoid damage to your vehicle, drive slowly,
readjust or remove the device if it's contacting your
vehicle, and don't spin your wheels.
If you do find traction devices that will fit, install
them on the rear tires.
If you have other size tires, use tire chains only
where legal and only when you must. Use only
SAE Class ªSº type chains that are the proper size
for your tires. Install them on the drive axle tires
(four
-wheel-drive vehicles can use chains on both
axles) and tighten them as tightly as possible with
the ends securely fastened. Drive slowly and follow
the chain manufacturer's instructions. If you can
hear the chains contacting your vehicle, stop and
retighten them. If the contact continues, slow down
until it stops. Driving too fast or spinning the
wheels with chains on will damage your vehicle.
Appearance Care
Remember, cleaning products can be hazardous. Some
are toxic. Others can burst into flame if you strike a
match or get them on a hot part of the vehicle. Some are
dangerous if you breathe their fumes in a closed space.
When you use anything from a container to clean your
vehicle, be sure to follow the manufacturer's warnings
and instructions. And always open your doors or
windows when you're cleaning the inside.
Never use these to clean your vehicle:

Gasoline

Benzene

Naphtha

Carbon Tetrachloride

Acetone

Paint Thinner

Turpentine

Lacquer Thinner

Nail Polish Remover
They can all be hazardous
-- some more than
others
-- and they can all damage your vehicle, too.

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9-2
BBB Auto Line 8-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Better Business Bureau Mediation 8-4 . . . . . . . . . . . . . . . . . . .
Blizzard, Driving In 4-39 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Brake Fluid 6-29 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Brake, Parking 2-33 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Brake System Warning Light 2-79 . . . . . . . . . . . . . . . . . . . . . .
Brakes
Adjustment 6
-32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Anti-Lock 4-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Master Cylinder 6-29 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pedal Travel 6-32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Replacing System Parts 6-33 . . . . . . . . . . . . . . . . . . . . . . . .
Trailer 4-50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wear 6-32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Brake-Transmission Shift Interlock Check 7-43 . . . . . . . . . . .
Braking 4-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Braking in Emergencies 4-8 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Break-In, New Vehicle 2-16 . . . . . . . . . . . . . . . . . . . . . . . . . .
Brightness Control 2-51 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BTSI Check 7-43 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Bulb Replacement 6-34, 6-65 . . . . . . . . . . . . . . . . . . . . . . . . .
Canadian Roadside Assistance 8-8 . . . . . . . . . . . . . . . . . . . .
Capacities and Specifications 6-65 . . . . . . . . . . . . . . . . . . . . . .
Carbon Monoxide 2-9, 2-38, 4-40, 4-51 . . . . . . . . . . . . . . . .
Care of Your Cassette Tape Player 3-42 . . . . . . . . . . . . . . . . . .
Cargo Cover 2-63 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cargo Tie Downs 2-63 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Center Front Passenger Position 1-30 . . . . . . . . . . . . . . . . . . . Certification/Tire Label 4
-42 . . . . . . . . . . . . . . . . . . . . . . . . . .
Chains
Safety 4
-50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tire 6-48 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Changing a Flat Tire 5-19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Charging System Light 2-77 . . . . . . . . . . . . . . . . . . . . . . . . . .
Check Gages Light 2-85 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Checking Your Restraint Systems 1-56 . . . . . . . . . . . . . . . . . .
Chemical Paint Spotting 6-56 . . . . . . . . . . . . . . . . . . . . . . . . . .
Child Restraints 1-42 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Center Seat Positions 1-50 . . . . . . . . . . . . . . . . . . . . . . . . . .
Securing in a Rear Outside Seat Position 1-48 . . . . . . . . . . .
Securing in the Right Front Seat Position 1-50 . . . . . . . . . .
Top Strap 1-47 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Where Not to Put 1-50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Where to Put 1-46 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cigarette Lighter 2-65 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Circuit Breakers and Fuses 6-59 . . . . . . . . . . . . . . . . . . . . . . .
Cleaner, Air 6-15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning
Aluminum Wheels 6
-55 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Exterior Lamps and Lenses 6-54 . . . . . . . . . . . . . . . . . . . . .
Fabric 6-50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Glass 6-52 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inside of Your Vehicle 6-50 . . . . . . . . . . . . . . . . . . . . . . . . .
Instrument Panel 6-52 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Interior Plastic Components 6-52 . . . . . . . . . . . . . . . . . . . . .
Leather 6-52 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Outside of Your Vehicle 6-53 . . . . . . . . . . . . . . . . . . . . . . . .
Stains 6-51 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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9-6
Inspections
Brake System 7-46 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Cooling System 7-45 . . . . . . . . . . . . . . . . . . . . . . . .
Exhaust Systems 7-45 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Drive Axle Boot Seal 7-45 . . . . . . . . . . . . . . . . . . . . .
Steering 7-45 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Suspension 7-45 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Throttle System 7-46 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transfer Case 7-46 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Instrument Panel 2-72 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning 6-52 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cluster 2-73, 2-74 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuse Block 6-60 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Interior Lamps 2-51 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Jacking Equipment 5-21 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Jump Starting 5-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Key in the Ignition 2-17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Key Lock Cylinders Service 7-42 . . . . . . . . . . . . . . . . . . . . . .
Key Release Button 2-18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Keyless Entry System 2-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Keys 2-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Labels
Certification/Tire 4-42 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuse 6-60, 6-62 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Safety Belt 1-57 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Service Parts Identification 6-58 . . . . . . . . . . . . . . . . . . . . .
Vehicle Identification Number 6-58 . . . . . . . . . . . . . . . . . . . Lamps 2
-48 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dome 2-51 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Map 2-51 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Reading 2-51, 2-56 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Interior 2-51 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
On Reminder 2-49 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Latches, Seatback 1-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Leaving Your Vehicle 2-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Leaving Your Vehicle with the Engine Running 2-36 . . . . . . .
Lighter 2-65 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lights
Air Bag Readiness 1
-25, 2-77 . . . . . . . . . . . . . . . . . . . . . . .
Anti-Lock Brake System Warning 2-80, 4-7 . . . . . . . . . . . .
Brake System Warning 2-79 . . . . . . . . . . . . . . . . . . . . . . . . .
Charging System 2-77 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Check Gages 2-85 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gate Ajar 2-85 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Low Fuel 2-86 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Safety Belt Reminder 1-11, 2-76 . . . . . . . . . . . . . . . . . . . . .
Security Warning 2-84 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Service 4WD 2-84 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Service Engine Soon 2-81 . . . . . . . . . . . . . . . . . . . . . . . . . .
Shift 2-26, 2-78 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Loading Your Vehicle 4-42 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Loading Your Vehicle for Off-Road Driving 4-15 . . . . . . . . . .
Locking Rear Axle 2-40 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lockout Prevention 2-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lockout Switch 2-41 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .