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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
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.
326 VEHICLE CARE
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.
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. See Maintenance Schedule 0 399.
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
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
VEHICLE CARE 327
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.
The coolant surge tank is in the
engine compartment on the passenger side of the vehicle. See Engine
Compartment Overview 0 309.
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 0 330.
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 0 330.
{ 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.
328 VEHICLE CARE
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
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)
VEHICLE CARE 329
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.
The coolant reservoir for the TPIM is filled with GM Premix DEX-COOL
coolant. See Recommended Fluids and
Lubricants 0 408. If using this mixture, nothing else needs to be added.
The coolant needs to be replaced at the appropriate interval. See
Maintenance Schedule 0 399.
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 0 309.
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.