2006 GMC SIERRA check engine

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.
Then, without shutting off the engine, follow these steps:
The transmission dipstick
handle with this graphic is
located at the rear of the
engine compartment, on
the passenger’s side of
the vehicle.
SeeEngine Compartment Overview on page 5-14for
more information on location.
1. Flip the handle up and then pull out the dipstick
and wipe it with a clean rag or paper towel.
2. Push it back in all the way, wait three seconds and
then pull it back out again.3. Check both sides of the dipstick, and read the lower
level. The uid level must be in the COLD area,
below the cross-hatched area, for a cold check or
in the HOT or cross-hatched area for a hot check.
Be sure to keep the dipstick pointed down to get an
accurate reading.
4. If the uid level is in the acceptable range, push the
dipstick back in all the way; then ip the handle down
to lock the dipstick in place.
Consistency of Readings
Always check the uid level at least twice using the
procedure described previously. Consistency (repeatable
readings) is important to maintaining proper uid level.
If inconsistent readings persist, check the transmission
breather hose to be sure it is clean and unclogged.
If readings are still inconsistent, contact your dealer.
5-29

How to Add Automatic
Transmission Fluid
Refer to the Maintenance Schedule to determine what
kind of transmission uid to use. SeeRecommended
Fluids and Lubricants (Gasoline Engine) on page 6-14.
Add uid only after checking the transmission uid
while it is hot. A cold check is used only as a reference.
If the uid level is low, add only enough of the proper
uid to bring the level up to the HOT area for a hot
check. It does not take much uid, generally less than
one pint (0.5 L). Do not overll.
Notice:Use of the incorrect automatic transmission
uid may damage your vehicle, and the damages
may not be covered by your warranty. Always
use the automatic transmission uid listed in
Recommended Fluids and Lubricants (Gasoline
Engine) on page 6-14.
After adding uid, recheck the uid level as
described under “How to Check Automatic
Transmission Fluid,” earlier in this section.
When the correct uid level is obtained, push the
dipstick back in all the way; then ip the handle
down to lock the dipstick in place.
Automatic Transmission Fluid
(Allison Transmission
®)
When to Check and Change Automatic
Transmission Fluid
A good time to check your automatic transmission uid
level is when the engine oil is changed.
Change the uid and lter at the intervals listed in
Additional Required Services (Gasoline Engine) on
page 6-7, and be sure to use the transmission uid
listed inRecommended Fluids and Lubricants
(Gasoline Engine) on page 6-14.
How to Check Automatic
Transmission Fluid
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.
5-30

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.
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, run the engine for
at least once minute and shift to DRIVE (D). Then
shift to NEUTRAL (N) and then REVERSE (R) to ll
the hydraulic system. Then, position the shift lever in
PARK (P).
4. Allow the engine to run at idle (500–800 rpm).
Slowly release the brake pedal.
Then, without shutting off the engine, follow these steps:
Cold Check Procedure
The purpose of the cold check is to determine if the
transmission has enough uid to be operated safely until
a hot check can be made. The uid level rises as uid
temperature increases. Do not ll above the COLD
CHECK band if the transmission uid is below normal
operating temperatures.
1. Pull out the dipstick and wipe it with a clean rag or
paper towel.
2. Push it back in all the way, wait three seconds and
then pull it back out again.
3. Check the uid level reading. Repeat the check
procedure to verify the reading.
5-31

How to Add Automatic
Transmission Fluid
Refer to the Maintenance Schedule to determine what
kind of transmission uid to use. SeeRecommended
Fluids and Lubricants (Gasoline Engine) on page 6-14.
Add uid only after checking the transmission uid
while it is hot. A cold check is used only as a reference.
If the uid level is low, add only enough of the proper
uid to bring the level up to the HOT area for a hot
check. It does not take much uid, generally less than
one pint (0.5 L). Do not overll.
Notice:Use of the incorrect automatic transmission
uid may damage your vehicle, and the damages
may not be covered by your warranty. Always use the
automatic transmission uid listed inRecommended
Fluids and Lubricants (Gasoline Engine) on
page 6-14.
After adding uid, recheck the uid level as described
under “How to Check Automatic Transmission Fluid,”
earlier in this section.
When the correct uid level is obtained, push the
dipstick back in all the way.
Manual Transmission Fluid
When to Check Manual
Transmission Fluid
A good time to have your manual transmission uid
checked is when the engine oil is changed. See
Additional Required Services (Gasoline Engine)
on page 6-7to nd out when to change your
transmission uid.
How to Check Manual
Transmission Fluid
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.
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.
5-33

Check the uid 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 ngers on the
transmission case.
Then, follow these steps:
1. Remove the ller plug.
2. Check that the lubricant level is up to the bottom of
the ller plug hole.
3. If the uid level is good, install the plug and be sure
it is fully seated. If the uid level is low, add more
uid as described in the next steps.How to Add Manual Transmission Fluid
Here is how to add uid. Refer to the Maintenance
Schedule to determine what kind of uid to use. See
Recommended Fluids and Lubricants (Gasoline Engine)
on page 6-14.
1. Remove the ller plug.
2. Add uid at the ller plug hole. Add only enough
uid to bring the uid level up to the bottom of the
ller plug hole.
3. Install the ller plug. Be sure the plug is fully
seated.
Hydraulic Clutch
The hydraulic clutch linkage in your vehicle is
self-adjusting. The clutch master cylinder reservoir
is lled with hydraulic clutch uid.
It is not necessary to regularly check clutch uid unless
you suspect there is a leak in the system. Adding uid will
not correct a leak.
A uid loss in this system could indicate a problem.
Have the system inspected and repaired. 5-speed for VORTEC™ 4300 V6 and 4800 V8 engines
shown, other manual transmissions similar
5-34

When to Check and What to Use
The clutch master cylinder
reservoir is located in
the rear of the engine
compartment on the
driver’s side of the vehicle.
SeeEngine Compartment
Overview on page 5-14
for more information on
location.
Refer to the Maintenance Schedule to determine how
often you should check the uid level in your clutch
master cylinder reservoir and for the proper uid.
SeeOwner Checks and Services on page 6-11and
Recommended Fluids and Lubricants (Gasoline Engine)
on page 6-14.
How to Check and Add Fluid
The proper uid should be added if the level does not
reach the bottom of the diaphragm when it is in place in
the reservoir. See the instructions on the reservoir cap.
Engine Coolant
The cooling system in your vehicle is lled with
DEX-COOL®engine coolant. This coolant is designed
to remain in your vehicle for ve years or 150,000 miles
(240 000 km), whichever occurs rst, if you add only
DEX-COOL
®extended life coolant.
The following explains your cooling system and how
to add coolant when it is low. If you have a problem
with engine overheating, seeEngine Overheating
on page 5-37.
A 50/50 mixture of clean, drinkable water and
DEX-COOL
®coolant will:
Give freezing protection down to−34°F (−37°C).
Give boiling protection up to 265°F (129°C).
Protect against rust and corrosion.
Help keep the proper engine temperature.
Let the warning lights and gages work as they
should.
Notice:Using coolant other than DEX-COOL
®may
cause premature engine, heater core, or radiator
corrosion. In addition, the engine coolant may
require changing sooner, at the rst maintenance
service after each 25,000 miles (41 500 km) or
24 months, whichever occurs rst. Any repairs
would not be covered by your warranty. Always use
DEX-COOL
®(silicate-free) coolant in your vehicle.
5-35

What to Use
Use a mixture of one-half clean, drinkable water and
one-half DEX-COOL®coolant which will not damage
aluminum parts. If you use this coolant mixture, you do
not need to add anything else.
{CAUTION:
Adding only plain water to your cooling
system can be dangerous. Plain water, or
some other liquid such as alcohol, can boil
before the proper coolant mixture will. Your
vehicle’s coolant warning system is set for the
proper coolant mixture. With plain water or the
wrong mixture, your engine could get too hot
but you would not get the overheat warning.
Your engine could catch re and you or others
could be burned. Use a 50/50 mixture of clean,
drinkable water and DEX-COOL
®coolant.
Notice:If you use an improper coolant mixture, your
engine could overheat and be badly damaged. The
repair cost would not be covered by your warranty.
Too much water in the mixture can freeze and crack
the engine, radiator, heater core and other parts.If you have to add coolant more than four times a year,
have your dealer check your cooling system.
Notice:If you use extra inhibitors and/or additives
in your vehicle’s cooling system, you could damage
your vehicle. Use only the proper mixture of the
engine coolant listed in this manual for the cooling
system. SeeRecommended Fluids and Lubricants
(Gasoline Engine) on page 6-14for more information.
Checking Coolant
The coolant surge tank is located in the engine
compartment on the passenger’s side of the vehicle.
SeeEngine Compartment Overview on page 5-14
for more information on location.
{CAUTION:
Turning the surge tank pressure cap when the
engine and radiator are hot can allow steam
and scalding liquids to blow out and burn you
badly. Never turn the surge tank pressure
cap — even a little — when the engine and
radiator are hot.
5-36

If the coolant inside the coolant surge tank is boiling,
do not do anything else until it cools down. The vehicle
should be parked on a level surface. Check the coolant
level after the system cools down. Some amount of
coolant may be lost due to overheating.
The coolant level should
be at or above the FULL
COLD mark. If it is not,
you may have a leak at
the pressure cap or in
the radiator hoses, heater
hoses, radiator, water
pump, or somewhere
else in the cooling system.
{CAUTION:
Heater and radiator hoses, and other engine
parts, can be very hot. Do not touch them.
If you do, you can be burned.
Do not run the engine if there is a leak. If you
run the engine, it could lose all coolant. That
could cause an engine re, and you could be
burned. Get any leak xed before you drive the
vehicle.
If your vehicle is equipped with an electric engine cooling
fan, check the coolant temperature gage. If the coolant
temperature is approximately 232°F (111°C), the electric
cooling fan should be running. If it is not, your vehicle
needs service. Turn off the engine.
5-41