2018 CADILLAC CT6 engine coolant

Cadillac CT6 Owner Manual (GMNA-Localizing-U.S./Canada-11292458) -
2018 - crc - 2/15/17
316 VEHICLE CARE
2. Keep turning the pressure capslowly 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
the upper radiator hose getting
hot. Watch out for the engine
cooling fan.
By this time, the coolant level
inside the coolant surge tank
may be lower. If the level is
lower, add more of the proper
mixture to the coolant surge
tank until the level reaches the
indicated level mark.
5. Replace the pressure cap tightly.
6. Verify coolant level after the engine is shut off and the
coolant is cold. If necessary,
repeat coolant fill procedure
Steps 1–6.
If the coolant still is not at the
proper level when the system
cools down again, see your
dealer.Caution
If the pressure cap is not tightly
installed, coolant loss and engine
damage may occur. Be sure the cap
is properly and tightly secured.
Cooling System
(PLUG-IN Only)
The cooling system allows the engine
and the Traction Power Inverter
Module (TPIM) to maintain the
correct working temperature.
1. Engine Coolant Surge Tank
and Pressure Cap
2. Traction Power Inverter Module (TPIM)
3. TPIM Coolant Reservoir and Pressure Cap
4. Engine Cooling Fan (Out of View)
{Warning
An underhood electric fan can start
up even when the engine is not
running and can cause injury. Keep
hands, clothing, and tools away
from any underhood electric fan.
{Warning
Do not touch heater or radiator
hoses, or other engine parts. They
can be very hot and can burn you.
Do not run the engine if there is a
leak; all coolant could leak out.
That could cause an engine fire and
can burn you. Fix any leak before
driving the vehicle.

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

Cadillac CT6 Owner Manual (GMNA-Localizing-U.S./Canada-11292458) -
2018 - crc - 2/15/17
VEHICLE CARE 319
the upper radiator hose getting
hot. Watch out for the engine
cooling fan.
By this time, the coolant level
inside the coolant surge tank
may be lower. If the level is
lower, add more of the proper
mixture to the coolant surge
tank until the level reaches the
indicated level mark.
5. Replace the pressure cap tightly.
6. Verify coolant level after the engine is shut off and the
coolant is cold. If necessary,
repeat coolant fill procedure
Steps 1–6.
If the coolant still is not at the
proper level when the system
cools down again, see your
dealer.
Caution
If the pressure caps are not secured
and tightened properly, coolant loss
and damage to the PLUG-IN cooling
(Continued)
Caution (Continued)
systems or vehicle may occur. Make
sure the caps are properly and
tightly secured.
PLUG-IN Coolant
The cooling system allows the TPIM
to maintain the correct working
temperature.
{Warning
An underhood electric fan can start
up even when the engine is not
running and can cause injury. Keep
hands, clothing, and tools away
from any underhood electric fan.
{Warning
Do not touch heater or radiator
hoses, or other engine parts. They
can be very hot and can burn you.
Do not run the engine if there is a
(Continued)
Warning (Continued)
leak; all coolant could leak out.
That could cause an engine fire and
can burn you. Fix any leak before
driving the vehicle.
The TPIM is cooled using a separate
coolant loop.
The TPIM is kept below a maximum
temperature. If the temperature rises
above this temperature, the electric
cooling fan will turn on to cool the
coolant.
What to Use 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.

Cadillac CT6 Owner Manual (GMNA-Localizing-U.S./Canada-11292458) -
2018 - crc - 2/15/17
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
334 VEHICLE CARE
FusesUsage
20 High-beam headlamp relay
21 Air conditioning clutch
22 –
23 Coolant heater control module
24 Coolant pump
25 Coolant pump relay
26 Hi fuel
27 Steering column lock
28 Rear heated seats
29 Front heated seats
30 –
31 LED lighting battery
32 Air conditioning control module
33 AIR solenoid
34 –
35 Engine control module Fuses
Usage
36 Engine control module 2
37 Coolant pump/ Ignition coils–odd
38 Ignition coils–even/ Non walk 2
39 Non walk
40 Instrument cluster
41 –
42 Fuel pump power module
43 Instrument panel body/Ignition
44 Aeroshutter
45 Washer
46 Front sensor
47 Left cornering LED
48 AIR solenoid relay
49 Air pump relay
50 Engine control module relay
51 Wiper speed relay Fuses
Usage
52 Wiper control relay
53 Headlamp control relay
54 –
55 –
56 Air pump
57 –
58 Instrument panel electronic center
59 –
60 Anitlock brake system pump
61 Front wiper
62 Headlamp leveling
63 Electric brake booster module
64 –
65 –
66 Transfer case control module
67 Electric brake booster