2006 GMC SIERRA check engine

If your vehicle is equipped with an engine-driven cooling
fan, start the engine again and see if the fan speed
increases when idle speed is doubled by pushing the
accelerator pedal down. If it does not, your vehicle
needs service. Turn off the engine.
Notice:Engine damage from running your engine
without coolant is not covered by your warranty.
SeeOverheated Engine Protection Operating Mode
(V8 Engines Only) on page 5-39for information
on driving to a safe place in an emergency.
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 30,000 miles (50 000 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.
How to Add Coolant to the Coolant
Surge Tank for Gasoline Engines
If your vehicle has a diesel engine, see “Cooling
System” in the DURAMAX®Diesel Supplement for
the proper coolant ll procedure.If you have not found a problem yet, check to see if
coolant is visible in the surge tank. If coolant is visible
but the coolant level is not at or above the FULL COLD
mark, add a 50/50 mixture of clean, drinkable water
and DEX-COOL
®coolant at the coolant surge tank,
but be sure the cooling system, including the coolant
surge tank pressure cap, is cool before you do it.
SeeEngine Coolant on page 5-35for more information.
If no coolant is visible in the surge tank, add coolant
as follows:
{CAUTION:
Steam and scalding liquids from a hot cooling
system can blow out and burn you badly. They
are under pressure, and if you turn the coolant
surge tank pressure cap — even a little — they
can come out at high speed. Never turn the
cap when the cooling system, including the
coolant surge tank pressure cap, is hot. Wait
for the cooling system and coolant surge tank
pressure cap to cool if you ever have to turn
the pressure cap.
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Engine Fan Noise
If your vehicle is equipped with 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 fan is spinning slower and the
clutch is not fully engaged. This improves fuel economy
and reduces fan noise. Under heavy vehicle loading,
trailer towing, and/or high outside temperatures, the fan
speed increases as the clutch more fully 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 partially
disengages.
If your vehicle is equipped with electric cooling fans,
you may hear the fans spinning at low speed during most
everyday driving. The fans may turn off if no cooling is
required. Under heavy vehicle loading, trailer towing,
and/or high outside temperatures, or if you are operating
your air conditioning system, the fans change to high
speed and you may hear an increase in fan noise.
This is normal and indicates that the cooling system is
functioning properly. The fans will change to low speed
when additional cooling is no longer required.
Power Steering Fluid
SeeEngine Compartment
Overview on page 5-14for
reservoir location.
When to Check Power Steering Fluid
It is not necessary to regularly check power steering uid
unless you suspect there is a leak in the system or you
hear an unusual noise. A uid loss in this system could
indicate a problem. Have the system inspected and
repaired.
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How to Check Power Steering Fluid
To check the power steering uid, do the following:
1. Turn the key off and let the engine compartment
cool down.
2. Wipe the cap and the top of the reservoir clean.
3. Unscrew the cap and wipe the dipstick with a
clean rag.
4. Replace the cap and completely tighten it.
5. Remove the cap again and look at the uid level on
the dipstick.
The level should be at the FULL COLD mark.
If necessary, add only enough uid to bring the
level up to the mark.
What to Use
To determine what kind of uid to use, see
Recommended Fluids and Lubricants (Gasoline Engine)
on page 6-14. Always use the proper uid. Failure to
use the proper uid can cause leaks and damage hoses
and seals.
Windshield Washer Fluid
What to Use
When you need windshield washer uid, be sure to read
the manufacturer’s instructions before use. If you will be
operating your vehicle in an area where the temperature
may fall below freezing, use a uid that has sufficient
protection against freezing.
Adding Washer Fluid
Your vehicle has a low washer uid message that
comes on when the washer uid is low. The message
is displayed for 15 seconds at the start of each
ignition cycle. When the CHECK WASHER FLUID
message is displayed, you will need to add washer
uid to the windshield washer uid reservoir.
5-46

So, it is not a good idea to top off your brake uid. Adding
brake uid will not correct a leak. If you add uid when
your linings are worn, then you will have too much uid
when you get new brake linings. You should add or
remove brake uid, as necessary, only when work is
done on the brake hydraulic system.
{CAUTION:
If you have too much brake uid, it can spill on
the engine. The uid will burn if the engine is
hot enough. You or others could be burned,
and your vehicle could be damaged. Add brake
uid only when work is done on the brake
hydraulic system. See “Checking Brake Fluid”
in this section.
Refer to the Maintenance Schedule to determine when
to check your brake uid. SeeScheduled Maintenance
(Gasoline Engine) on page 6-4.
Checking Brake Fluid
You can check the brake uid without taking off the cap.
Just look at the brake uid
reservoir. The uid level
should be above MIN.
If it is not, have your brake
system checked to see
if there is a leak.
After work is done on the brake hydraulic system,
make sure the level is above the MIN but not over
the MAX mark.
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Notice:Ignoring these steps could result in costly
damage to your vehicle that would not be covered
by your warranty.
Trying to start your vehicle by pushing or pulling it
will not work, and it could damage your vehicle.
1. Check the other vehicle. It must have a 12-volt
battery with a negative ground system.
Notice:If the other vehicle’s system is not a 12-volt
system with a negative ground, both vehicles can
be damaged. Only use vehicles with 12-volt systems
with negative grounds to jump start your vehicle.
2. If you have a vehicle with a diesel engine with two
batteries (or more), you should know before you
begin that, especially in cold weather, you may not
be able to get enough power from a single battery in
another vehicle to start your diesel engine.
If your vehicle has more than one battery, use the
battery that is closer to the starter — this will reduce
electrical resistance.3. Get the vehicles close enough so the jumper cables
can reach, but be sure the vehicles are not touching
each other. If they are, it could cause a ground
connection you do not want. You would not be able
to start your vehicle, and the bad grounding
could damage the electrical systems.
To avoid the possibility of the vehicles rolling, set
the parking brake rmly on both vehicles involved in
the jump start procedure. Put an automatic
transmission in PARK (P) or a manual transmission
in NEUTRAL before setting the parking brake.
If you have a four-wheel-drive vehicle, be sure the
transfer case
is in a drive gear, not in NEUTRAL.
Notice:If you leave your radio or other accessories
on during the jump starting procedure, they could
be damaged. The repairs would not be covered
by your warranty. Always turn off your radio and
other accessories when jump starting your vehicle.
4. Turn off the ignition on both vehicles. Unplug
unnecessary accessories plugged into the cigarette
lighter or accessory power outlets. Turn off the radio
and all lamps that are not needed. This will avoid
sparks and help save both batteries. And it could
save the radio!
5-53

{CAUTION:
Fans or other moving engine parts can injure
you badly. Keep your hands away from moving
parts once the engine is running.
6. Check that the jumper cables do not 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 (+) or a remote positive terminal (+) if the
vehicle has one. Negative (−) will go to a heavy,
unpainted metal engine part or a remote negative (−)
terminal if the vehicle has one.
Do not connect positive (+) to negative (−) or you will
get a short that would damage the battery and maybe
other parts too. And do not connect the negative (−)
cable to the negative (−) terminal on the dead battery
because this can cause sparks.
On vehicles equipped with dual batteries, make all
battery connections to the remote positive (+) and
remote negative (−) terminals.7. Connect the red
positive (+) cable to
the positive (+) terminal
of the vehicle with the
dead battery. Use a
remote positive (+)
terminal if the vehicle
has one.
8. Do not let the other end touch metal. Connect it to
the positive (+) terminal of the good battery. Use a
remote positive (+) terminal if the vehicle has one.
9. Now connect the black negative (−) cable to the
negative (−) terminal of the good battery. Use a
remote negative (−) terminal if the vehicle has one.
The vehicle’s remote negative (–) terminal is
marked GND.
5-55

Rear Axle
When to Check Lubricant
It is not necessary to regularly check rear axle uid
unless you suspect there is a leak or you hear an
unusual noise. A uid loss could indicate a problem.
Have it inspected and repaired.
All axle assemblies are lled by volume of uid during
production. They are not lled to reach a certain level.
When checking the uid level on any axle, variations in
the readings can be caused by factory ll differences
between the minimum and the maximum uid volume.
Also, if a vehicle has just been driven before checking the
uid level, it may appear lower than normal because uid
has traveled out along the axle tubes and has not drained
back to the sump area. Therefore, a reading taken ve
minutes after the vehicle has been driven will appear to
have a lower uid level than a vehicle that has been
stationary for an hour or two. Remember that the rear
axle assembly must be supported to get a true reading.
How to Check Lubricant
To get an accurate reading, the vehicle should be on a
level surface.
The proper level for the 1500 Series is from
5/8 inch to 1 5/8 inch (15 mm to 40 mm) below
the bottom of the ller plug hole.
The proper level for the 1500HD Series,
2500 Series and 2500HD Series with the
6.0L V8 engine (RPO LQ4) is from 0 to 1/2 inch
(0 to 13 mm) below the bottom of the ller plug hole.1500 Series Shown, 2500 Series Similar
5-58

The proper level for the 2500HD with the 6.6L diesel
engine (RPO LLY) or 8.1L V8 engine (RPO L18), and
3500 Series is from 0.6 to 0.8 inch (17 mm to 21 mm)
below the bottom of the ller plug hole.
Add only enough uid to reach the proper level.
What to Use
To determine what kind of lubricant to use see
Recommended Fluids and Lubricants (Gasoline Engine)
on page 6-14.
Four-Wheel Drive
Lubricant checks in this section also apply to these
vehicles. There are two additional systems that need
lubrication.
Transfer Case
When to Check Lubricant
It is not necessary to regularly check transfer case uid
unless you suspect there is a leak or you hear an unusual
noise. A uid loss could indicate a problem. Have it
inspected and repaired.
How to Check Lubricant
Manual Transfer Case
5-59