heat BUICK LACROSSE 2015 Service Manual

Black plate (18,1)Buick LaCrosse Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
7707475) - 2015 - CRC - 10/9/14
10-18 Vehicle Care
3.6L V6 Engine AWD
1. Engine Cooling Fans (Outof View)
2. Coolant Surge Tank and Pressure Cap
3.6L V6 Engine FWD
1. Engine Cooling Fans (Outof View)
2. Coolant Surge Tank and Pressure Cap
{Warning
An electric engine cooling fan
under the hood 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
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 engine 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.
{Caution
Using coolant other than
DEX-COOL®can cause
premature engine, heater core,
or radiator corrosion. In addition,
the engine coolant could require
changing sooner. Any repairs
would not be covered by the
(Continued)

Black plate (19,1)Buick LaCrosse Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
7707475) - 2015 - CRC - 10/9/14
Vehicle Care 10-19
Caution (Continued)
vehicle warranty. Always use
DEX-COOL (silicate-free) coolant
in the vehicle.
Engine Coolant
The cooling system in the vehicle is
filled with DEX-COOL®engine
coolant mixture. See Recommended
Fluids and Lubricants on page 11-12
and Maintenance Schedule on
page 11-2.
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 on
page 10-21.
What to Use
{Warning
Adding only plain water or some
other liquid to the cooling system
can be dangerous. Plain water
and other liquids, can boil before
the proper coolant mixture will.
The coolant warning system is set
for the proper coolant mixture.
With plain water or the wrong
mixture, the engine could get too
hot but you would not get the
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.
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
temperature.
{Caution
If improper coolant mixture,
inhibitors, or additives are used in
the vehicle cooling system, the
engine could overheat and be
damaged. Too much water in the
mixture can freeze and crack
engine cooling parts. The repairs
would not be covered by the
vehicle warranty. Use only the
(Continued)

Black plate (20,1)Buick LaCrosse Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
7707475) - 2015 - CRC - 10/9/14
10-20 Vehicle Care
Caution (Continued)
proper mixture of engine coolant
for the cooling system. See
Recommended Fluids and
Lubricants on page 11-12.
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. If coolant is visible but the coolant
level is not at or above the mark
pointed to, add a 50/50 mixture of
clean, drinkable water and
DEX-COOL coolant.
Be sure the cooling system is cool
before this is done.
If no coolant is visible in the coolant
surge tank, add coolant as follows:
How to Add Coolant to the
Coolant Surge Tank
{Warning
You can be burned if you spill
coolant on hot engine parts.
Coolant contains ethylene glycol
and it will burn if the engine parts
are hot enough. Do not spill
coolant on a hot engine.
{Caution
This vehicle has a specific
coolant fill procedure. Failure to
follow this procedure could cause
the engine to overheat and be
severely damaged.
{Warning
Steam and scalding liquids from a
hot cooling system can blow out
and burn you badly. Never turn
the cap when the cooling system,
including the surge tank pressure
cap, is hot. Wait for the cooling
system and surge tank pressure
cap to cool.

Black plate (21,1)Buick LaCrosse Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
7707475) - 2015 - CRC - 10/9/14
Vehicle Care 10-21
The coolant surge tank pressure
cap can be removed when the
cooling system, including the surge
tank pressure cap and upper
radiator hose, is no longer hot.
1. Turn the pressure cap slowlycounterclockwise. If a hiss is
heard, wait for that to stop.
A hiss means there is still some
pressure left.
2. Keep turning the cap and remove it.
3. Fill the coolant surge tank withthe proper mixture to the mark
pointed to on the front of the
coolant surge tank.
4. With the coolant surge tank cap off, start the engine and let it run
until the upper radiator hose
starts getting hot. Watch out for
the engine cooling fans. 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 mark pointed to on
the front of the coolant
surge tank.
5. Replace the cap tightly.
{Caution
If the pressure cap is not tightly
installed, coolant loss and
possible engine damage may
occur. Be sure the cap is properly
and tightly secured.
Engine Overheating
There is a coolant temperature
gauge and a engine coolant
temperature warning light on the
instrument cluster that indicate an
overheated engine condition. See
Engine Coolant Temperature Gauge
on page 5-13 andEngine Coolant
Temperature Warning Light on
page 5-22.

Black plate (22,1)Buick LaCrosse Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
7707475) - 2015 - CRC - 10/9/14
10-22 Vehicle Care
If the decision is made not to lift the
hood when this warning appears,
get service help right away. See
Roadside Assistance Program on
page 13-5.
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 fans are running. If the
engine is overheating, the fans
should be running. If not, do not
continue to run the engine and have
the vehicle serviced.
{Caution
Running the engine without
coolant may cause damage or a
fire. Vehicle damage would not be
covered by the vehicle warranty.
If Steam Is Coming from the
Engine Compartment
SeeOverheated Engine Protection
Operating Mode on page 10-23 for
information on driving to a safe
place in an emergency.
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 might 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.
.Tows a trailer. If the overheat warning displays 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 temperature overheat gauge is
no longer in the overheat zone or an
engine coolant temperature warning
light no longer displays, the vehicle
can be driven. Continue to drive the
vehicle slowly for about 10 minutes.
Keep a safe vehicle 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.

Black plate (23,1)Buick LaCrosse Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
7707475) - 2015 - CRC - 10/9/14
Vehicle Care 10-23
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. Also, seeOverheated
Engine Protection Operating Mode
on page 10-23.
Overheated Engine
Protection
Operating Mode
This emergency operating mode
allows the vehicle to be driven to a
safe place in an emergency
situation. If an overheated engine
condition exists, an overheat
protection mode which alternates
firing groups of cylinders helps
prevent engine damage. In this
mode, there is significant loss in
power and engine performance. The engine coolant temperature
warning light comes on the
instrument panel, to indicate the
vehicle has entered overheated
engine protection operating mode.
The temperature gauge also
indicates an overheat condition
exists. Driving extended distances
and/or towing a trailer in the
overheat protection mode should be
avoided.
Power Steering Fluid
(2.4L L4 Engine and 3.6L
V6 Engine with FWD)
The vehicle has electric power
steering and does not use power
steering fluid.
Power Steering Fluid
(3.6L V6 Engine
with AWD)
See
Engine Compartment Overview
on page 10-6 for information on the
location of the power steering fluid
reservoir.
When to Check Power Steering
Fluid
It is not necessary to regularly
check power steering fluid unless a
leak is suspected in the system or
an unusual noise is heard. A fluid
loss in this system could indicate a
problem. Have the system inspected
and repaired.

Black plate (35,1)Buick LaCrosse Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
7707475) - 2015 - CRC - 10/9/14
Vehicle Care 10-35
Electrical System
Overload
The vehicle has fuses and circuit
breakers to protect against an
electrical system overload.
When the current electrical load is
too heavy, the circuit breaker opens
and closes, protecting the circuit
until the current load returns to
normal or the problem is fixed. This
greatly reduces the chance of circuit
overload and fire caused by
electrical problems.
Fuses and circuit breakers protect
power devices in the vehicle.
Replace a bad fuse with a new one
of the identical size and rating.
If there is a problem on the road and
a fuse needs to be replaced, the
same amperage fuse can be
borrowed. Choose some feature of
the vehicle that is not needed to use
and replace it as soon as possible.
Headlamp Wiring
An electrical overload may cause
the lamps to go on and off, or in
some cases to remain off. Have the
headlamp wiring checked right away
if the lamps go on and off or
remain off.
Windshield Wipers
If the wiper motor overheats due to
heavy snow or ice, the windshield
wipers will stop until the motor cools
and will then restart.
Although the circuit is protected
from electrical overload, overload
due to heavy snow or ice may
cause wiper linkage damage.
Always clear ice and heavy snow
from the windshield before using the
windshield wipers.
If the overload is caused by an
electrical problem and not snow or
ice, be sure to get it fixed.
Fuses and Circuit
Breakers
The wiring circuits in the vehicle are
protected from short circuits by a
combination of fuses and circuit
breakers. This greatly reduces the
chance of damage caused by
electrical problems.
To check a fuse, look at the
silver-colored band inside the fuse.
If the band is broken or melted,
replace the fuse. Be sure to replace
a bad fuse with a new one of the
identical size and rating.
Fuses of the same amperage can
be temporarily borrowed from
another fuse location, if a fuse goes
out. Replace the fuse as soon as
possible.
To identify and check fuses, circuit
breakers, and relays, seeEngine
Compartment Fuse Block on
page 10-36 andInstrument Panel
Fuse Block on page 10-40.

Black plate (37,1)Buick LaCrosse Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
7707475) - 2015 - CRC - 10/9/14
Vehicle Care 10-37
J-CaseFuses Usage
25 Rear Heated Seats
26 Antilock Brake System Pump
27 Electric Parking Brake
28 Rear Window Defogger
41 Brake Vacuum Pump
42 Cooling Fan K2
43 Not Used
44 Transmission Auxiliary Oil Pump
(eAssist)
45 Cooling Fan K1
59 AIR Pump Mini Fuses Usage
1 Transmission Control Module —
Battery
2 Engine Control Module Battery
3 Air Conditioning Compressor Clutch
5 Engine Control Module Run/Crank
7 Long Range Radar/ Front Camera
8 Ignition Coils –Even
(Six Cylinder
Engine), Ignition
Coils –All (Four
Cylinder Engine)
9 Ignition Coils –Odd
(Six Cylinder
Engine) Mini Fuses Usage
10 Engine Control Module–Switched
Battery (from Engine
Control Module
Relay)
11 Six Cylinder Engine: Post Catalytic
Converter Oxygen
Sensor Heater,
Mass Air Flow
Sensor, FlexFuel
Sensor, Secondary
Air Induction
Solenoid
13 Crank for Transmission
Control Module/Fuel
Pump Power/
Chassis Control
Module (eAssist)

Black plate (38,1)Buick LaCrosse Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
7707475) - 2015 - CRC - 10/9/14
10-38 Vehicle Care
Mini Fuses Usage14 Cabin Heater Coolant Pump
(eAssist)/Secondary
Air Injector/
Secondary Air
Injector with
Pressure Sensor
15 Motor Generator Unit Coolant Pump
(eAssist)
16 Run/Crank for eAssist Power
Inverter Module
17 Not Used
18 Sunshade Module, Vehicle Air
Purification System,
Ventilated Seats
20 Heated Steering Wheel (non eAssist) Mini Fuses Usage
23 Variable Effort Steering (if
equipped) or eAssist
Power Inverter
Module
29 Heated Seat, Left/ Power Lumbar
30 Heated Seat, Right/ Power Pack Cooling
Fan (eAssist)
31 All-Wheel Drive, Electronic
Suspension Control
32 Body Control Module 6
33 Memory Seat –
Front
34 Antilock Brake System Valves
35 Amplifier
36 Adaptive Forward Lighting (AFL)
Motors–Battery Mini Fuses Usage
37 Right High Beam
38 Left High Beam
46 Cooling Fan Relay
47 Six Cylinder Engine: Pre Catalytic
Converter Oxygen
Sensor Heater,
Canister Purge
Solenoid. Four
Cylinder Engine: Pre
and Post Catalytic
Converter Oxygen
Sensor Heaters,
Canister Purge
Solenoid
48 Fog Lamps
49 Right High Intensity Discharge
Headlamp
50 Left High Intensity Discharge
Headlamp
51 Horn

Black plate (39,1)Buick LaCrosse Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
7707475) - 2015 - CRC - 10/9/14
Vehicle Care 10-39
Mini Fuses Usage52 Cluster Run/Crank
53 Run/Crank for Inside Rearview Mirror,
Rear Vision Camera,
Air Quality Sensor,
Aero Shutter Motor
54 Run/Crank for: Heating, Ventilation
and Air
Conditioning,
Headlamp Switch
55 Outside Rearview Mirror, Universal
Remote System,
Front Window
Switches
56 Windshield Washer
60 Heated Mirror
62 Canister Vent
64 Adaptive Forward Lighting (AFL)
Module–Battery
65 Not Used Mini Fuses Usage
66 AIR Solenoid (eAssist)
67 Fuel Pump Power Module/Chassis
Control Module
69 Regulated Voltage Control Sensor
70 Parking Assist/Side Blind Zone
71 Passive Entry/ Passive Start
Mini Relays Usage 7 Engine Control Module
9 Cooling Fan
13 Cooling Fan
15 Run/Crank
16 AIR Pump
17 Rear Window Defogger Micro
Relays Usage
1 Air Conditioning Compressor Clutch
2 Starter
4 Wiper Speed
5 Wiper Control
6 Cabin Heater Coolant Pump
(eAssist)/Secondary
Air Injector/
Secondary Air
Injector with
Pressure Sensor
10 Cooling Fan
14 Headlamp Low Beam
Ultra Micro Relays Usage
11 Transmission Auxiliary Oil Pump
(eAssist)