Vehicle Care 239
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.
The coolant level should be up to
the cold fill line. If it is not, there
might be a leak at the radiator
hoses, heater hoses, radiator, water
pump, or somewhere else in the
cooling system.
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Warning
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 vehicle if there is a
leak. If you run the engine, it
could lose all coolant. That could
cause an engine fire, and you
could be burned. Get any leak
fixed before you drive the vehicle.
If there seems to be no leak, with
the engine on, check to see if the
cooling fans are running. If the
engine is overheating, the fans
should be running. If it is not, the
vehicle needs service. Turn off the
vehicle.
Cooling System (High
Voltage Battery)
During vehicle operation and also
during charging, the high voltage
battery cells in the vehicle are kept
within a normal operating
temperature range. If the high
voltage battery cell temperature
rises above the normal operating
temperature range, the battery
cooling system turns on the air
conditioning compressor and cools
the coolant until the correct battery
cell temperature is reached. If the
high voltage battery cell temperature
falls below the normal operating
temperature range, a high voltage
heater, located in the battery, heats
the coolant until the correct battery
cell temperature is reached.
During high voltage battery system
cooling, you may feel temperature
changes at the air vents due to the
extra load on the system.
What to Use
The high voltage battery coolant
reservoir in the vehicle is filled with
GM Premix DEX-COOL
®
engine
coolant. See Recommended Fluids
and Lubricants 0 326. If using this
mixture, nothing else needs to be
added.
The coolant needs to be replaced at
the appropriate interval. See
Maintenance Schedule 0 317.
Checking Coolant
The vehicle must be on a level
surface when checking the coolant
level.
The high voltage battery coolant
reservoir is located in the engine
compartment. See Engine
Compartment Overview 0 233.