wiring BUICK LACROSSE 2015 Owner's Manual

Black plate (31,1)Buick LaCrosse Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
7707475) - 2015 - CRC - 10/9/14
Seats and Restraints 3-31
is on the seat. If the passenger
frontal airbag is turned on, the
on indicator will be lit.
If the passenger seat gets wet, dry
the seat immediately. If the airbag
readiness light is lit, do not install a
child restraint or allow anyone to
occupy the seat. See Airbag
Readiness Light on page 5-14 for
important safety information.
The on indicator may be lit if an
object, such as a briefcase,
handbag, grocery bag, laptop or
other electronic device, is put on an
unoccupied seat. If this is not
desired remove the object from
the seat.
{Warning
Stowing of articles under the
passenger seat or between the
passenger seat cushion and
seatback may interfere with the
proper operation of the passenger
sensing system.
Servicing the
Airbag-Equipped Vehicle
Airbags affect how the vehicle
should be serviced. There are parts
of the airbag system in several
places around the vehicle. Your
dealer and the service manual have
information about servicing the
vehicle and the airbag system. To
purchase a service manual, see
Service Publications Ordering
Information on page 13-11.
{Warning
For up to 10 seconds after the
vehicle is turned off and the
battery is disconnected, an airbag
can still inflate during improper
service. You can be injured if you
are close to an airbag when it
inflates. Avoid yellow connectors.
They are probably part of the
airbag system. Be sure to follow
(Continued)
Warning (Continued)
proper service procedures, and
make sure the person performing
work for you is qualified to do so.
Adding Equipment to the
Airbag-Equipped Vehicle
Adding accessories that change the
vehicle's frame, bumper system,
height, front end, or side sheet
metal, may keep the airbag system
from working properly. The
operation of the airbag system can
also be affected by changing any
parts of the front seats, safety belts,
the airbag sensing and diagnostic
module, steering wheel, instrument
panel, any of the airbag modules,
ceiling or pillar garnish trim, front
sensors, side impact sensors,
or airbag wiring.

Black plate (32,1)Buick LaCrosse Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
7707475) - 2015 - CRC - 10/9/14
3-32 Seats and Restraints
Your dealer and the service manual
have information about the location
of the airbag sensors, sensing and
diagnostic module, and airbag
wiring.
In addition, the vehicle has a
passenger sensing system for the
front outboard passenger position,
which includes sensors that are part
of the passenger seat. The
passenger sensing system may not
operate properly if the original seat
trim is replaced with non-GM
covers, upholstery, or trim; or with
GM covers, upholstery, or trim
designed for a different vehicle. Any
object, such as an aftermarket seat
heater or a comfort-enhancing pad
or device, installed under or on top
of the seat fabric, could also
interfere with the operation of the
passenger sensing system. This
could either prevent proper
deployment of the passenger
airbag(s) or prevent the passenger
sensing system from properlyturning off the passenger airbag(s).
See
Passenger Sensing System on
page 3-26.
If the vehicle has rollover roof-rail
airbags, see Different Size Tires
and Wheels on page 10-60 for
additional important information.
If you have to modify your vehicle
because you have a disability and
you have questions about whether
the modifications will affect the
vehicle's airbag system, or if you
have questions about whether the
airbag system will be affected if the
vehicle is modified for any other
reason, call Customer Assistance.
See Customer Assistance Offices
on page 13-3.
Airbag System Check
The airbag system does not need
regularly scheduled maintenance or
replacement. Make sure the airbag
readiness light is working. See
Airbag Readiness Light on
page 5-14.
{Caution
If an airbag covering is damaged,
opened, or broken, the airbag
may not work properly. Do not
open or break the airbag
coverings. If there are any
opened or broken airbag
coverings, have the airbag
covering and/or airbag module
replaced. For the location of the
airbags, see Where Are the
Airbags? on page 3-22. See your
dealer for service.
Replacing Airbag System
Parts after a Crash
{Warning
A crash can damage the airbag
systems in the vehicle.
A damaged airbag system may
not work properly and may not
(Continued)

Black plate (14,1)Buick LaCrosse Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
7707475) - 2015 - CRC - 10/9/14
5-14 Instruments and Controls
This reading indicates the same
thing as the warning light. It means
that the engine coolant has
overheated. If the vehicle has been
operating under normal driving
conditions, pull off the road, stop the
vehicle, and turn off the engine as
soon as possible. SeeEngine
Overheating on page 10-21 for more
information.
Safety Belt Reminders
Driver Safety Belt Reminder
Light
There is a driver safety belt
reminder light on the instrument
cluster.
When the vehicle is started, this
light flashes and a chime may come
on to remind the driver to fasten their safety belt. Then the light stays
on solid until the belt is buckled.
This cycle may continue several
times if the driver remains or
becomes unbuckled while the
vehicle is moving.
If the driver safety belt is buckled,
neither the light nor the chime
comes on.
Passenger Safety Belt
Reminder Light
There is a passenger safety belt
reminder light near the passenger
airbag status indicator. See
Passenger Sensing System on
page 3-26.
When the vehicle is started, this
light flashes and a chime may come
on to remind passengers to fasten
their safety belt. Then the light stayson solid until the belt is buckled.
This cycle continues several times if
the passenger remains or becomes
unbuckled while the vehicle is
moving.
If the passenger safety belt is
buckled, neither the chime nor the
light comes on.
The front passenger safety belt
reminder light and chime may turn
on if an object is put on the seat
such as a briefcase, handbag,
grocery bag, laptop, or other
electronic device. To turn off the
reminder light and/or chime, remove
the object from the seat or buckle
the safety belt.
Airbag Readiness Light
This light shows if there is an
electrical problem with the airbag
system. The system check includes
the airbag sensor(s), passenger
sensing system, the pretensioners,
the airbag modules, the wiring, and
the crash sensing and diagnostic

Black plate (1,1)Buick LaCrosse Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
7707475) - 2015 - CRC - 10/9/14
Vehicle Care 10-1
Vehicle Care
General Information
General Information . . . . . . . . . . 10-2
California Proposition65 Warning . . . . . . . . . . . . . . . . . 10-3
California Perchlorate Materials Requirements . . . . 10-3
Accessories and Modifications . . . . . . . . . . . . . . . 10-3
Vehicle Checks
Doing Your OwnService Work . . . . . . . . . . . . . . . 10-4
Hood . . . . . . . . . . . . . . . . . . . . . . . . 10-5
Engine Compartment Overview . . . . . . . . . . . . . . . . . . . 10-6
Engine Oil . . . . . . . . . . . . . . . . . . 10-11
Engine Oil Life System . . . . . 10-13
Automatic Transmission Fluid . . . . . . . . . . . . . . . . . . . . . . 10-15
Engine Air Cleaner/Filter . . . . 10-15
Cooling System . . . . . . . . . . . . 10-17
Engine Coolant . . . . . . . . . . . . . 10-19
Engine Overheating . . . . . . . . 10-21
Overheated Engine Protection
Operating Mode . . . . . . . . . . . 10-23 Power Steering Fluid (2.4L
L4 Engine and 3.6L
V6 Engine with FWD) . . . . . 10-23
Power Steering Fluid (3.6L V6 Engine with AWD) . . . . . 10-23
Washer Fluid . . . . . . . . . . . . . . . 10-24
Brakes . . . . . . . . . . . . . . . . . . . . . 10-25
Brake Fluid . . . . . . . . . . . . . . . . . 10-26
Battery . . . . . . . . . . . . . . . . . . . . . 10-27
All-Wheel Drive . . . . . . . . . . . . . 10-28
Starter Switch Check . . . . . . . 10-28
Automatic Transmission Shift Lock Control Function
Check . . . . . . . . . . . . . . . . . . . . . 10-29
Ignition Transmission Lock Check . . . . . . . . . . . . . . . . . . . . . 10-29
Park Brake and P (Park) Mechanism Check . . . . . . . . 10-29
Wiper Blade Replacement . . . . . . . . . . . . . . 10-30
Windshield Replacement . . . 10-30
Headlamp Aiming
Headlamp Aiming . . . . . . . . . . 10-31
Bulb Replacement
Bulb Replacement . . . . . . . . . . 10-31
Halogen Bulbs . . . . . . . . . . . . . . 10-31 High Intensity Discharge
(HID) Lighting . . . . . . . . . . . . . 10-31
LED Lighting . . . . . . . . . . . . . . . 10-31
Headlamps, Front Turn Signal and Parking
Lamps . . . . . . . . . . . . . . . . . . . . 10-32
Taillamps, Turn Signal, Stoplamps, and Back-Up
Lamps . . . . . . . . . . . . . . . . . . . . 10-33
License Plate Lamp . . . . . . . . 10-33
Replacement Bulbs . . . . . . . . . 10-34
Electrical System
High Voltage Devices and Wiring . . . . . . . . . . . . . . . . . . . . . 10-34
Electrical System Overload . . . . . . . . . . . . . . . . . . 10-35
Fuses and Circuit Breakers . . . . . . . . . . . . . . . . . . 10-35
Engine Compartment Fuse Block . . . . . . . . . . . . . . . . . . . . . 10-36
Instrument Panel Fuse Block . . . . . . . . . . . . . . . . . . . . . 10-40
Wheels and Tires
Tires . . . . . . . . . . . . . . . . . . . . . . . . 10-42
All-Season Tires . . . . . . . . . . . . 10-43
Winter Tires . . . . . . . . . . . . . . . . 10-43
Summer Tires . . . . . . . . . . . . . . 10-43

Black plate (33,1)Buick LaCrosse Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
7707475) - 2015 - CRC - 10/9/14
Vehicle Care 10-33
3. Pull the bulb straight out fromthe socket.
4. Reverse Steps 1–3 to install.
Taillamps, Turn Signal,
Stoplamps, and Back-Up
Lamps
1. Back-Up Lamp
2. Turn Signal Lamp
To replace one of these lamps:
1. Open the trunk. See Trunk on
page 2-13.
2. Remove the fasteners and pull back the trunk trim.
3. Remove the four plastic wing nuts holding the taillamp
assembly in place.
4. Pull out the taillamp assembly and disconnect the wiring
harness.
5. Turn the bulb socket counterclockwise to remove it.
6. Pull the old bulb straight out of the bulb socket.
7. Reverse Steps 1–6 to install.License Plate Lamp
The license plate lamps for this
vehicle are on the trunk lid.
To replace one of these bulbs:
1. Open the trunk. See Trunk on
page 2-13.
2. Push the end on either of the lamp assemblies (passenger
side shown) and then move the
lamp assembly down to remove
it from the trunk lid.

Black plate (34,1)Buick LaCrosse Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
7707475) - 2015 - CRC - 10/9/14
10-34 Vehicle Care
3. Turn the bulb socket (1)counterclockwise to remove it
from the lamp assembly (3).
4. Pull the bulb (2) straight out of the bulb socket.
5. Push the replacement bulb straight into the bulb socket and
turn the bulb socket clockwise to
install it into the lamp assembly.
6. Move the lamp assembly into the trunk lid, engaging the clip
side first.
7. Push on the lamp side opposite the clip until the lamp assembly
snaps into place.
Replacement Bulbs
Exterior Lamp Bulb
Number
Back-Up Lamp 921LL (W16W)
Front Turn
Signal Lamp 7444NA
Headlamp High
Beam (Base) HIR2
Headlamp Low
Beam (Base) HIR2
License Plate Lamp W5WLL
Rear Turn Signal 7443NA (WY21W)
For replacement bulbs not listed
here, contact your dealer.
Electrical System
High Voltage Devices and
Wiring
{Warning
Exposure to high voltage can
cause shock, burns, and even
death. The high voltage
components in the vehicle can
only be serviced by technicians
with special training.
High voltage components are
identified by labels. Do not
remove, open, take apart,
or modify these components.
High voltage cable or wiring has
orange covering. Do not probe,
tamper with, cut, or modify high
voltage cable or wiring.

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 (6,1)Buick LaCrosse Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
7707475) - 2015 - CRC - 10/9/14
i-6 INDEX
Headlamps (cont'd)Flash-to-Pass . . . . . . . . . . . . . . . . . . 6-2
High Intensity Discharge
(HID) Lighting . . . . . . . . . . . . . 10-31
High-Beam On Light . . . . . . . . . . 5-25
High/Low Beam Changer . . . . . . 6-2
Lamps On Reminder . . . . . . . . . 5-25
Heated Steering Wheel . . . . . . . . . . . . . . . . 5-3
Heated and Ventilated Front Seats . . . . . . . . . . . . . . . . . . . . . . . . . 3-9
Heated Mirrors . . . . . . . . . . . . . . . . . 2-19
Heater Engine . . . . . . . . . . . . . . . . . . . . . . . . 9-22
High Voltage Devices and Wiring . . . . . . . . . . . . . . . . . . . . . . . 10-34
High-Beam On Light . . . . . . . . . . . 5-25
High-Speed Operation . . . . . . . . 10-51
Hill and Mountain Roads . . . . . . . . 9-7
Hill Start Assist (HSA) . . . . . . . . . 9-33
Hood . . . . . . . . . . . . . . . . . . . . . . . . . . 10-5
Horn . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3
How to Wear Safety Belts Properly . . . . . . . . . . . . . . . . . . . . . . 3-14I
Ignition Positions . . . . . . . . 9-15, 9-16
Ignition Transmission LockCheck . . . . . . . . . . . . . . . . . . . . . . . 10-29
Immobilizer . . . . . . . . . . . . . . . . . . . . 2-16
Indicator Vehicle Ahead . . . . . . . . . . . . . . . . 5-21
Infants and Young Children, Restraints . . . . . . . . . . . . . . . . . . . . 3-35
Information Energy . . . . . . . . . . . . . . . . . . . . . . . 5-27
Infotainment . . . . . . . . . . . . . . . . . . . . 7-1
Infotainment System . . . . . . . . . . 13-15
Instrument Cluster . . . . . . . . . . . . . . 5-8
Interior Rearview Mirrors . . . . . . . 2-19
Introduction . . . . . . . . . . . . . . . . . . . . . . . iii
J
Jump Starting . . . . . . . . . .10-78, 10-79
K
Key and Lock Messages . . . . . . . 5-39
Keyless Entry Remote (RKE) System . . . . . . . . 2-3
Keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
L
Labeling, Tire Sidewall . . . . . . . . 10-44
Lamps Daytime Running (DRL) . . . . . . . 6-2
Dome . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5
Exterior Controls . . . . . . . . . . . . . . . 6-1
Exterior Lamps OffReminder . . . . . . . . . . . . . . . . . . . . 6-2
Fog . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4
Headlamps, Front Turn Signal, and Parking
Lamps . . . . . . . . . . . . . . . . . . . . 10-32
License Plate . . . . . . . . . . . . . . . 10-33
Malfunction Indicator . . . . . . . . . 5-16
Messages . . . . . . . . . . . . . . . . . . . . 5-40

Black plate (13,1)Buick LaCrosse Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
7707475) - 2015 - CRC - 10/9/14
INDEX i-13
TractionControl System (TCS)/
StabiliTrak
®Light . . . . . . . . . . . . 5-22
Limited-Slip Differential . . . . . . . 9-36
Off Light . . . . . . . . . . . . . . . . . . . . . . 5-21
Selective Ride Control . . . . . . . . 9-36
Traction Control/Electronic
Stability Control . . . . . . . . . . . . . . 9-34
Trailer Towing . . . . . . . . . . . . . . . . . . 9-66, 9-67
Transmission
Automatic . . . . . . . . . . . . . . . . . . . . . 9-27
Fluid, Automatic . . . . . . . . . . . . 10-15
Messages . . . . . . . . . . . . . . . . . . . . 5-44
Transportation Program, Courtesy . . . . . . . . . . . . . . . . . . . . . 13-7
Trunk . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13
Turn and Lane-Change Signals . . . . . . . . . . . . . . . . . . . . . . . . 6-4
Turn Signal Bulb Replacement . . . . . . . . . . 10-33
U
Uniform Tire Quality
Grading . . . . . . . . . . . . . . . . . . . . . 10-60
Universal Remote System . . . . . 5-51 Operation . . . . . . . . . . . . . . . . . . . . . 5-53
Programming . . . . . . . . . . . . . . . . . 5-51
Using This Manual . . . . . . . . . . . . . . . . iii
V
Vehicle
Alarm System . . . . . . . . . . . . . . . . 2-15
Canadian Owners . . . . . . . . . . . . . . . iii
Control . . . . . . . . . . . . . . . . . . . . . . . . 9-3
IdentificationNumber (VIN) . . . . . . . . . . . . . . . 12-1
Load Limits . . . . . . . . . . . . . . . . . . . 9-10
Messages . . . . . . . . . . . . . . . . . . . . 5-35
Personalization . . . . . . . . . . . . . . . 5-45
Remote Start . . . . . . . . . . . . . . . . . . 2-9
Security . . . . . . . . . . . . . . . . . . . . . . 2-15
Speed Messages . . . . . . . . . . . . . 5-44
Towing . . . . . . . . . . . . . . . . . . . . . . 10-82
Vehicle Ahead Indicator . . . . . . . 5-21 Vehicle Care
Storing the Tire Sealant
and Compressor Kit . . . . . . . 10-72
Tire Pressure . . . . . . . . . . . . . . . 10-50
Vehicle Data Recording and Privacy . . . . . . . . . . . . . . . . . 13-14
Vehicle Diagnostics
OnStar
®. . . . . . . . . . . . . . . . . . . . . . 14-6
Ventilation, Air . . . . . . . . . . . . . . . . . . 8-6
Visors . . . . . . . . . . . . . . . . . . . . . . . . . 2-22
Voltage Devices and Wiring . . . . . . . . . . . . . . . . . . . . . . . 10-34
W
WarningBrake System Light . . . . . . . . . . . 5-19
Lane Departure (LDW) . . . . . . . 9-57
Warning Lights, Gauges, and
Indicators . . . . . . . . . . . . . . . . . . . . . 5-7
Warnings . . . . . . . . . . . . . . . . . . . . . . . . . iv Cautions and Danger . . . . . . . . . . . .iv
Hazard Flashers . . . . . . . . . . . . . . . 6-4
Washer Fluid . . . . . . . . . . . . . . . . . 10-24

Black plate (14,1)Buick LaCrosse Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
7707475) - 2015 - CRC - 10/9/14
i-14 INDEX
WheelsAlignment and Tire
Balance . . . . . . . . . . . . . . . . . . . 10-62
Different Size . . . . . . . . . . . . . . . 10-60
Replacement . . . . . . . . . . . . . . . 10-62
When It Is Time for New Tires . . . . . . . . . . . . . . . . . . . . . . . . 10-57
Where to Put the Restraint . . . . 3-39
Windows . . . . . . . . . . . . . . . . . . . . . . 2-20 Messages . . . . . . . . . . . . . . . . . . . . 5-44
Power . . . . . . . . . . . . . . . . . . . . . . . . 2-20
Windshield Replacement . . . . . . . . . . . . . . . 10-30
Wiper/Washer . . . . . . . . . . . . . . . . . 5-3
Winter Driving . . . . . . . . . . . . . . . . . . . . . . . . . 9-8
Winter Tires . . . . . . . . . . . . . . . . . . 10-43
Wiper Blade Replacement . . . . 10-30
Wiring, High Voltage Devices . . . . . . . . . . . . . . . . . . . . . 10-34