1998 GMC SIERRA transmission

Automatic Transmission Fluid
If your vehicle has a diesel engine, see “Automatic
Transmission Fluid”
in the Diesel Supplement.
When to Check and Change
A good time to check your automatic transmission fluid
level is when the engine oil is changed.
Change both the fluid and filter every
50,000 miles
(83
000 km) if the vehicle’s GVWR is over 8,600 or
if the vehicle is mainly driven under one or more of
these conditions:
In heavy city traffic where the outside temperature
In hilly or mountainous terrain.
When doing frequent trailer towing.
Uses such as found in taxi, police or delivery service.
regularly
reaches
90°F (32°C) or higher.
If your vehicle’s GVWR is not over 8,600 and you do not
use your vehicle under any
of these conditions, change the
fluid and filter every
100,000 miles (166 000 km).
See “Scheduled Maintenance Services’’ in the Index.
How to Check
Because this operation can be a little difficult, you
may choose to have this done at your
GM 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 fluid can damage your
transmission.
Too much can mean that some of
the fluid could come
out and fall on hot engine
parts or exhaust system parts, starting a fire.
Be
sure to get an accurate reading if you check your
transmission fluid.
Wait at least 30 minutes before checking the
transmission fluid 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 fluid should be at normal
operating temperature, which is
180°F to 200°F (82°C
to 93°C). See “Checking Transmission Fluid Hot“ in
the Index.
6-21
ProCarManuals.com

Checking Transmission Fluid Hot
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 (IOOC), drive the
vehicle in THIRD
(3) until the engine temperature gage
moves and then remains steady for 10 minutes. Then
follow
the hot check procedures.
Checking Transmission Fluid Cold
A cold check is made after the vehicle has been sitting
for eight hours or more with the engine off and is used
only as a reference. Let the engine run at idle for five
minutes if outside temperatures are 50°F (10°C) or
more.
If it's colder than 50°F ( 1 O"C), you may have
to idle the engine longer. Should the fluid level be low
during
a cold check, you must perform a hot check
before adding fluid. This will give you
a more accurate
reading of the fluid level.
Checking the Fluid Hot or Cold
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, move the shift
lever through each gear range, pausing for about three seconds
in each range.
Then, position the shift
lever
in PARK (P).
Let the engine run at idle for three minutes or more.
Then, without shutting
off the engine, follow these steps:
1. The red transmission dipstick handle is located at the
rear
of the engine compartment, on the passenger's
side. Flip the handle up and then
pull out the dipstick
and wipe
it with a clean rag or paper towel.
then pull it back out again.
2. Push it back in all the way, wait three seconds and
6-22
ProCarManuals.com

3. Check both sides of the dipstick, and read the lower
level. The fluid level must be in the COLD area for a
cold check or in the
HOT area or cross-hatched area
for a
hot check.
4. If the fluid level is in the acceptable range, push the
dipstick back in all the way; then flip the handle
down
to lock the dipstick in place.
io dd Fluid
Refer to the Maintenance Schedule to determine what
kind
of transmission fluid to use. See “Recommended
Fluids and Lubricants”
in the Index. Add
fluid only after checking the transmission fluid
while
it is hot. (A cold check is used only as a
reference.)
If the fluid level is low, add only enough of
the proper fluid
to bring the level up to the HOT area for
a hot check. It doesn’t take much fluid, generally less
than one pint
(0.5 L). Don’t overfill.
I NOTICE:
We recommend you use only fluid labeled
DEXRON@-111, because fluid with that label is
made especially for your automatic transmission.
Damage caused by fluid other than DEXRON-111
is not covered by your new vehicle warranty.
After adding fluid, recheck the fluid level as
described under “How to Check.”
When the correct fluid level is obtained, push the
dipstick back
in all the way; then flip the handle
down to lock the dipstick
in place.
6-23
ProCarManuals.com

Manual Transmission Fluid
When to Check
A good time to have it checked is when the engine oil is
changed. However, the fluid in your manual
transmission doesn’t require changing.
How to Check
Because this operation can be a little difficult, you
may choose to have this done at your GM dealership
Service Department.
If you do it yourself, be sure to follow all the
instructions here, or you could get a fdse reading.
NOTICE:
Too much or too little fluid can damage your
transmission.
Too much can mean that some of
the fluid could come out and fall on hot engine
parts or exhaust system parts, starting a fire. Be
sure to get an accurate reading if you check your
transmission fluid.
Check the fluid level only when your engine is off, the
vehicle is parked on a level place and the transmission is
cool enough
for you to rest your fingers on the
transmission case.
Then, follow these steps:
I. Remove the filler plug.
2. Check that the lubricant level is up to the bottom of
the filler plug hole.
3. If the fluid level is good, install the plug and be sure
it is fully seated. If the fluid level is low, add more
fluid as described in the next steps.
6-24
ProCarManuals.com

Fuse/Circuit Breaker Usage
20
21
22
23
24
A
B
PRNDL, Automatic Transmission,
Speedometer, Check Gages
Warning Light
Security/Steering
Not Used
Not Used
Front Axle,
4WD Indicator Lamp,
TP2 Relay (Gasoline Engine)
Power Door Lock, Six-Way Power Seat, Keyless Entry Module
Power Windows
Underhood Fuse/Relay Center
The underhood fusehelay center is located in the rear of
the engine compartment near the brake fluid reservoir.
Move the retainer clips
for the cover to access the
fuse block.
You can remove fuses with a fuse extractor. The fuse
extractor
is mounted to the interior fuse block. TO
remove fuses
if you don’t have a fuse extractor, hold the
end of the fuse between your thumb and index finger
and pull straight out.
6-74
ProCarManuals.com

Maintenance Schedule
Short Trip/City Definition -- Gasoline Engines
Follow the Short Trip/City Maintenance Schedule if any
one of these conditions is true for your vehicle:
Most trips are less than 5 to 10 miles (8 to I6 km).
This is particularly important when outside
temperatures are below freezing.
Most trips include extensive idling (such as frequent
driving
in stop-and-go traffic).
You operate your vehicle in dusty areas or
off-road frequently.
You frequently tow a trailer.
If the vehicle is used for delivery service, police, taxi
or other commercial application.
One oj*tlw reclsorzs yo14 sl~or.~ld~foIlo~~~ this scI~edniv if
you operate yo1.w vehicle urlcler CIIZJ ojthese cor-zditions
is that these cwm1ition.s CCJLIS~ eqirw oil to break
dOC1!12 Sool-zel:
Short Trip/City Intervals -- Gasoline Engines
Every
3,000 Miles (5 000 km): Engine Oil and Filter
Change (or 3 months, whichever occurs first). Chassis
Lubrication (or 3 months, whichever occurs first).
Drive Axle Service (or 3 months, whichever
occurs first).
Every 6,000 Miles (10 000 km): Tire Rotation.
Every 15,000 Miles (25 000 km): Shields and
Underhood Insulation Inspection (GVWR above
8,500 lbs. only). Front Wheel Bearing Repack
(2WD only) (or at each brake relining, whichever
occurs first).
Every 30,000 Miles (50 000 km): Fuel Filter
Every 50,000 Miles (83 000 km): Automatic
Replacement.
Transmission Service (vehicles over
8600 GVWR or
driven under severe conditions only).
Every 60,000 Miles (100 000 km): Engine Accessory
Drive Belt Inspection. Fuel Tank, Cap and Lines
Inspection. Exhaust Gas Recirculation System
Inspection. Evaporative Control System Inspection.
ProCarManuals.com

Maintenance Schedule
I Short Trip/City Intervals -- Gasoline Engines I
Every 100,000 Miles (166 000 km): Spark Plug Wire
Inspection. Spark
Plug Replacement. Automatic
Transmission Service (normal conditions). Positive
Crankcase Ventilation
(PCV) Valve Inspection.
Every 150,000 Miles (240 000 km): Cooling System
Service (or every
60 months, whichever occurs first). Follow this maintenance
schedule
only if none of the
conditions from the Short Trip/City Maintenance
Schedule is true.
Do not use this schedule if the vehicle
is used for trailer towing, driven in a dusty area or used
off paved roads. Use the Short Trip/City schedule for
these conditions.
Driving CI Ldzicle r+*ith CI fL1ly warmed engine urzder
highvvcry conditions
causes engine oil to break
dowm slorvcr.
7-6
ProCarManuals.com

Maintenance Schedule
Long TriplHighway Intervals -- Gasoline Engines
Every
7,500 Miles (12 500 km): Engine Oil and Filter
Change (or every 12 months, whichever occurs first).
Chassis Lubrication (or every
12 months, whichever
occurs first). Drive Axle Service. Tire Rotation.
Every 15,000 Miles (25 000 km): Shields and
Underhood Insulation Inspection (GVWR above
8,500 lbs. only).
Every 30,000 Miles (50 000 km): Fuel Filter
Replacement. Front Wheel Bearing Repack
(2WD only) (or at each brake relining, whichever
occurs first).
Every 50,000 Miles (83 000 km): Automatic
Transmission Service (vehicles over
8600 GVWR
or driven under severe conditions only).
I Long; TripMighway Intervals -- Gasoline Engines I
Every 60,000 Miles (100 000 km): Engine Accessory
Drive Belt Inspection. Fuel Tank, Cap and Lines
Inspection. Exhaust Gas Recirculation System
Inspection. Evaporative Control System Inspection.
Every 100,000 Miles (166 000 km): Spark Plug Wire
Inspection. Spark Plug Replacement. Automatic
Transmission Service (normal conditions). Positive
Crankcase Ventilation (PCV) Valve Inspection.
Every 150,000 Miles (240 000 km): Cooling System
Service (or every
60 months, whichever occurs first).
These intervals only summarize maintenance services.
Be sure to follow the complete maintenance schedule on
the following pages.
7-7
ProCarManuals.com