2018 CADILLAC CT6 check engine

Cadillac CT6 Owner Manual (GMNA-Localizing-U.S./Canada-11292458) -
2018 - crc - 2/15/17
314 VEHICLE CARE
Engine Coolant
The engine cooling system in the
vehicle is filled with a DEX-COOL
engine coolant mixture. This coolant
needs to be checked and replaced at
appropriate intervals. SeeMaintenance
Schedule 0390.
The following explains the cooling
system and how to check and add
coolant when it is low. If there is a
problem with engine overheating, see
Engine Overheating 0321.
What to Use
{Warning
Plain water, or other liquids such as
alcohol, can boil before the proper
coolant mixture will. With plain
water or the wrong mixture, the
engine could get too hot but there
would not be an overheat warning.
The engine could catch fire and you
or others could be burned. Use a 50/50 mixture of clean,
drinkable water and DEX-COOL
coolant. If using this mixture, nothing
else needs to be added. This mixture:
.
Gives freezing protection down to
−37 °C (−34 °F), outside
temperature
. Gives boiling protection up to
129 °C (265 °F), engine
temperature
. Protects against rust and corrosion
. Will not damage aluminum parts
. Helps keep the proper engine
temperatureCaution
Do not use anything other than a
mix of DEX-COOL coolant that
meets GM Standard GMW3420 and
clean, drinkable water. Anything
else can cause damage to the
vehicle’s engine cooling system and
vehicle, which would not be covered
by the vehicle warranty. Never dispose of engine coolant by
putting it in the trash, pouring it on
the ground, or into sewers, streams,
or bodies of water. Have the coolant
changed by an authorized service
center, familiar with legal
requirements regarding used coolant
disposal. This will help protect the
environment and your health.
Checking Coolant
The vehicle must be on a level surface
when checking the coolant level.
2.0L L4 and 3.0L V6 Engine Coolant
Surge Tank

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VEHICLE CARE 315
3.6L V6 Engine Coolant Surge Tank
Check to see if coolant is visible in the
coolant surge tank. If the coolant
inside the coolant surge tank is
boiling, do not do anything else until
it cools down. See Engine Overheating
0 321.
The coolant surge tank is in the
engine compartment on the passenger
side of the vehicle. See Engine
Compartment Overview 0300.
How to Add Coolant to the
Coolant Surge Tank
If no problem is found, check to see if
coolant is visible in the coolant surge
tank. If coolant is visible but not at or above the indicated mark, add a 50/
50 mixture of clean, drinkable water
and DEX-COOL coolant. Be sure the
cooling system, including the coolant
surge tank pressure cap, is cool before
this is done. See
Engine Overheating
0 321.
{Warning
Spilling coolant on hot engine parts
can burn you. Coolant contains
ethylene glycol and it will burn if
the engine parts are hot enough.
{Warning
Steam and scalding liquids from a
hot cooling system are under
pressure. Turning the pressure cap,
even a little, can cause them to
come out at high speed and you
could be burned. Never turn the cap
when the cooling system, including
the pressure cap, is hot. Wait for
the cooling system and pressure
cap to cool.
Caution
Failure to follow the specific
coolant fill procedure could cause
the engine to overheat and could
cause system damage. If coolant is
not visible in the surge tank,
contact your dealer.
1. Remove the coolant surge tank
pressure cap when the cooling
system, including the coolant
surge tank pressure cap and
upper radiator hose, is no
longer hot.
Turn the pressure cap slowly
counterclockwise about
one-quarter of a turn. If you hear
a hiss, wait for that to stop. This
will allow any pressure still left
to be vented out the
discharge hose.

Cadillac CT6 Owner Manual (GMNA-Localizing-U.S./Canada-11292458) -
2018 - crc - 2/15/17
VEHICLE CARE 317
Engine Coolant
The engine cooling system in the
vehicle is filled with GM Premix
DEX-COOL coolant. This coolant
needs to be checked and replaced at
appropriate intervals. SeeMaintenance
Schedule 0390.
The following explains the cooling
system and how to check and add
coolant when it is low. If there is a
problem with engine overheating, see
Engine Overheating 0321.
What to Use
{Warning
Plain water, or other liquids such as
alcohol, can boil before the proper
coolant mixture will. With plain
water or the wrong mixture, the
engine could get too hot but there
would not be an overheat warning.
The engine could catch fire and you
or others could be burned.
Use GM Premix DEX-COOL coolant.
If using this mixture, nothing else
needs to be added. This mixture: .
Gives freezing protection down to
−37 °C (−34 °F), outside
temperature
. Gives boiling protection up to
129 °C (265 °F), engine
temperature
. Protects against rust and corrosion
. Will not damage aluminum parts
. Helps keep the proper engine
temperature
Caution
Do not use anything other than GM
Premix DEX-COOL coolant.
Anything else can cause damage to
the PLUG-IN cooling system
components and the vehicle, which
would not be covered by the vehicle
warranty.
Never dispose of engine coolant by
putting it in the trash, pouring it on
the ground, or into sewers, streams,
or bodies of water. Have the coolant
changed by an authorized service
center, familiar with legal requirements regarding used coolant
disposal. This will help protect the
environment and your health.
Checking Coolant
The vehicle must be on a level surface
when checking the coolant level.
Check to see if coolant is visible in the
coolant surge tank. If the coolant
inside the coolant surge tank is
boiling, do not do anything else until
it cools down. See
Engine Overheating
0 321.

Cadillac CT6 Owner Manual (GMNA-Localizing-U.S./Canada-11292458) -
2018 - crc - 2/15/17
318 VEHICLE CARE
The coolant surge tank is in the
engine compartment on the passenger
side of the vehicle. SeeEngine
Compartment Overview 0300.
How to Add Coolant to the
Coolant Surge Tank
If no problem is found, check to see if
coolant is visible in the coolant surge
tank. If coolant is visible but not at or
above the indicated mark, add GM
Premix DEX-COOL coolant. Be sure
the cooling system, including the
coolant surge tank pressure cap, is
cool before this is done. See Engine
Overheating 0321.
{Warning
Spilling coolant on hot engine parts
can burn you. Coolant contains
ethylene glycol and it will burn if
the engine parts are hot enough.
{Warning
Steam and scalding liquids from a
hot cooling system are under
pressure. Turning the pressure cap,
even a little, can cause them to
come out at high speed and you
could be burned. Never turn the cap
when the cooling system, including
the pressure cap, is hot. Wait for
the cooling system and pressure
cap to cool.
Caution
Failure to follow the specific
coolant fill procedure could cause
the engine to overheat and could
cause system damage. If coolant is
not visible in the surge tank,
contact your dealer.
1. Remove the coolant surge tank
pressure cap when the cooling
system, including the coolant
surge tank pressure cap and
upper radiator hose, is no
longer hot.
Turn the pressure cap slowly
counterclockwise about
one-quarter of a turn. If you hear
a hiss, wait for that to stop. This
will allow any pressure still left
to be vented out the
discharge hose.
2. Keep turning the pressure cap slowly and remove it.
3. Fill the coolant surge tank with the proper mixture to the
indicated level mark.
4. With the coolant surge tank pressure cap off, start the engine
and let it run until you can feel

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320 VEHICLE CARE
The coolant reservoir for the TPIM is
filled with GM Premix DEX-COOL
coolant. SeeRecommended Fluids and
Lubricants 0399. If using this mixture,
nothing else needs to be added.
The coolant needs to be replaced at
the appropriate interval. See
Maintenance Schedule 0390.
Checking Coolant
The vehicle must be on a level surface
when checking the coolant level.
The coolant reservoir is in the engine
compartment. See Engine Compartment
Overview 0300.
Check to see if coolant is visible in the
reservoir. If coolant is visible but the
coolant level is below the indicated
mark, there could be a leak in the
cooling system.
Caution
Do not run the engine when there
is a leak in the PLUG-IN cooling
system. This can cause a loss of all
coolant and can damage the system
and the vehicle. Have any leaks
fixed right away.
How to Add Coolant to the
Coolant Reservoir
If no problem is found, add the proper
DEX-COOL coolant mixture at the
coolant reservoir.
The coolant reservoir pressure cap can
be removed when the cooling system,
including the pressure cap, is no
longer hot.
1. Turn the pressure cap counterclockwise and remove it.
2. Fill the coolant reservoir with the proper mixture to the indicated
mark on the side of the reservoir.
3. Reinstall the pressure cap tightly.
Caution
If the pressure caps are not secured
and tightened properly, coolant loss
and damage to the PLUG-IN cooling
systems or vehicle may occur. Make
sure the caps are properly and
tightly secured.
Check the level in the coolant
reservoir when the cooling system has
cooled down. If the coolant is not at
the proper level, repeat Steps 1 and 2,
then reinstall the pressure cap. If the
coolant still is not at the proper level
when the system cools down again,
see your dealer.

Cadillac CT6 Owner Manual (GMNA-Localizing-U.S./Canada-11292458) -
2018 - crc - 2/15/17
VEHICLE CARE 321
Engine Overheating
The vehicle has several indicators to
warn of the engine overheating.
There is an engine coolant
temperature gauge and an engine
coolant temperature warning light on
the instrument cluster.
SeeEngine Coolant Temperature Gauge
0 139 and Engine Coolant Temperature
Warning Light 0149. The vehicle may
also display a message on the Driver
Information Center (DIC).
If the decision is made not to lift the
hood when this warning appears, get
service help right away. See Roadside
Service 0411.
If the decision is made to lift the
hood, make sure the vehicle is parked
on a level surface. Then check to see if
the engine cooling fan is running.
If the engine is overheating, the fan
should be running. If it is not, do not
continue to run the engine. Have the
vehicle serviced.Caution
Do not run the engine if there is a
leak in the engine cooling system.
This can cause a loss of all coolant
and can damage the system and
vehicle. Have any leaks fixed
right away.
If Steam Is Coming from the
Engine Compartment
{Warning
Steam and scalding liquids from a
hot cooling system are under
pressure. Turning the pressure cap,
even a little, can cause them to
come out at high speed and you
could be burned. Never turn the cap
when the cooling system, including
the pressure cap, is hot. Wait for
the cooling system and pressure
cap to cool.
If No Steam Is Coming from the
Engine Compartment
If an engine overheat warning is
displayed but no steam can be seen or
heard, the problem may not be too
serious. Sometimes the engine can get
a little too hot when the vehicle:
. Climbs a long hill on a hot day
. Stops after high-speed driving
. Idles for long periods in traffic
If the overheat warning is displayed
with no sign of steam: 1. Turn the air conditioning off.
2. Turn the heater on to the highest temperature and to the highest
fan speed. Open the windows as
necessary.
3. When it is safe to do so, pull off the road, shift to P (Park) or
N (Neutral), and let the
engine idle.
If the engine coolant temperature
gauge is no longer in the overheated
area or the engine coolant
temperature warning light no longer
displays, the vehicle can be driven.
Continue to drive the vehicle slowly

Cadillac CT6 Owner Manual (GMNA-Localizing-U.S./Canada-11292458) -
2018 - crc - 2/15/17
322 VEHICLE CARE
for about 10 minutes. Keep a safe
distance from the vehicle in front.
If the warning does not come back on,
continue to drive normally and have
the cooling system checked for proper
fill and function.
If the warning continues, pull over,
stop, and park the vehicle right away.
If there is no sign of steam, idle the
engine for three minutes while parked.
If the warning is still displayed, turn
off the engine until it cools down.
Washer Fluid
What to Use
When windshield washer fluid is
needed, be sure to read the
manufacturer's instructions before
use. If operating the vehicle in an area
where the temperature may fall below
freezing, use a fluid that has sufficient
protection against freezing.
Adding Washer Fluid
Open the cap with the washer symbol
on it. Add washer fluid until the tank
is full. SeeEngine Compartment
Overview 0300 for reservoir location.
Caution
.
Do not use washer fluid that
contains any type of water
repellent coating. This can
cause the wiper blades to
chatter or skip.
. Do not use engine coolant
(antifreeze) in the windshield
washer. It can damage the
windshield washer system
and paint.
. Do not mix water with
ready-to-use washer fluid.
Water can cause the solution
(Continued)
Caution (Continued)
to freeze and damage the
washer fluid tank and other
parts of the washer system.
. When using concentrated
washer fluid, follow the
manufacturer instructions for
adding water.
. Fill the washer fluid tank only
three-quarters full when it is
very cold. This allows for
fluid expansion if freezing
occurs, which could damage
the tank if it is
completely full.
Brakes
Disc brake pads have built-in wear
indicators that make a high-pitched
warning sound when the brake pads
are worn and new pads are needed.
The sound can come and go or can be
heard all the time when the vehicle is
moving, except when applying the
brake pedal firmly.

Cadillac CT6 Owner Manual (GMNA-Localizing-U.S./Canada-11292458) -
2018 - crc - 2/15/17
VEHICLE CARE 323
{Warning
The brake wear warning sound
means that soon the brakes will not
work well. That could lead to a
crash. When the brake wear
warning sound is heard, have the
vehicle serviced.
Caution
Continuing to drive with worn-out
brake pads could result in costly
brake repair.
Some driving conditions or climates
can cause a brake squeal when the
brakes are first applied or lightly
applied. This does not mean
something is wrong with the brakes.
Properly torqued wheel nuts are
necessary to help prevent brake
pulsation. When tires are rotated,
inspect brake pads for wear and
evenly tighten wheel nuts in the proper sequence to torque
specifications. See
Capacities and
Specifications 0404.
Brake pads should be replaced as
complete sets.
Brake Pedal Travel
See your dealer if the brake pedal does
not return to normal height, or if
there is a rapid increase in pedal
travel. This could be a sign that brake
service may be required.
Replacing Brake System Parts
Always replace brake system parts
with new, approved replacement parts.
If this is not done, the brakes may not
work properly. The braking
performance expected can change in
many other ways if the wrong
replacement brake parts are installed
or if parts are improperly installed.
Brake Fluid
The brake master cylinder reservoir is
filled with GM approved DOT 3 (for
gasoline only vehicles) or DOT 4 (for
PLUG-IN vehicles) brake fluid as
indicated on the reservoir cap. See
Engine Compartment Overview 0300
for the location of the reservoir.
Checking Brake Fluid
With the vehicle in P (Park) on a level
surface, the brake fluid level should be
between the minimum and maximum
marks on the brake fluid reservoir.
There are only two reasons why the
brake fluid level in the reservoir may
go down:
. Normal brake lining wear. When
new linings are installed, the fluid
level goes back up.