2024 GMC SIERRA DENALI brake

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16908340) - 2024 - CRC - 12/7/22
396 Service and Maintenance
‐Any vehicle consistently operated in a
high sand or dust environment such as
those used on oil pipelines and similar
applications.
.Vehicles that are regularly used for short
trips of 6 km (4 mi) or less.
The oil life indicator will show you when
to change the oil and filter. Under severe
conditions the indicator may come on
before 12 000 km (7,500 mi).
* Footnote: Under extreme driving
conditions listed above, it may be
necessary to replace your spark plugs at
more frequent intervals. For further
assistance in determining the most
suitable service maintenance intervals for
your vehicle, please contact your
authorized GM Dealer.
Extreme service is for vehicles mainly
driven off-road in four-wheel drive or used
in farming, mining, forestry, or snow
plowing.
Additional Required Services –Severe
Service
Every 40 000 km (25,000 mi)
.Change transfer case fluid, if equipped
with 4WD. Do not directly power wash
the transfer case and/or front/rear axle
output seals. High pressure water can
overcome the seals and contaminate the
transfer case fluid. Contaminated fluid will
decrease the life of the transfer case
and/or axles and should be replaced.
Every 72 000 km (45,000 mi)
.Change automatic transmission fluid and
filter.
Owner Checks and Services
Every Five Years
.Replace brake fluid.
Every Seven Years
.Replace Air Conditioning Desiccant every
seven years. The air conditioning system
requires maintenance every seven years.
This service requires replacement of the
desiccant to help the longevity and
efficient operation of the air conditioning
system. This service can be complex. See
your dealer.
Multi-Point Vehicle
Inspection (MPVI)
A Multi Point Vehicle Inspection (MPVI)
completed by a GM dealer technician is a
maintenance assessment of your vehicle.
The benefit of the MPVI is to identify and
inform the customer of service items that
require immediate attention and those that
may require attention in the future.
The technician will perform the following
checks on your vehicle. For a complete list
of checks, inspections, and services, see your
dealer.
Some items may not apply to your vehicle
and/or region.
Diagnostics
.OnStar active, if equipped
.Service history/recall check
Engine Oil and Filter
.Engine oil
.Oil life monitor
‐ Reset oil life monitor
Exterior Lights
.Visual inspection

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16908340) - 2024 - CRC - 12/7/22
Service and Maintenance 397
Windshield and Wipers
.Visual inspection
Battery
.Battery visual inspection
.Battery test results
.Battery cables and connections
Systems, Fluids, and Visible Leak
Inspection
.Engine oil
.Transmission
.Drive axle
.Transfer case
.Engine cooling system
.Power steering, if equipped
.Fuel system
.Windshield washer fluid
Tire Inspection
.Tire pressure, tread depth, and wear
.Rotation, if applicable
.Alignment check, optional
.Reset tire pressure monitor
.Check tire sealant expiration date,
if equipped
.Check spare tire, if equipped
Brakes
.Check brake system
Visible and Functional Inspections
.Seat belt components
.Exhaust system
.Accelerator pedal
.Passenger compartment air filter,
if equipped
.Engine air filter
.Hoses
.Belts
.Shocks and struts
.Steering components
.Axle boots or driveshaft and u-joints
.Compartment lift struts, if equipped
.Floor mats secured, no interference with
pedals
.Horn
.Ignition lock, if equipped
.Starter switch
.Evaporative control system
Lubricate
.Chassis components
Special Application Services
.Vehicles with Dual Wheels: Check dual
wheel nut torque at 160, 1 600, and
10 000 km (100, 1,000, and 6,000 mi) of
driving. Repeat this service whenever a
tire/wheel is serviced or removed.
.Severe Commercial Use Vehicles Only:
Lubricate chassis components every oil
change.
.Have underbody flushing service
performed. See “Underbody Maintenance”
in Exterior Care 0383.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16908340) - 2024 - CRC - 12/7/22
398 Service and Maintenance
Recommended Fluids, Lubricants, and Parts
Recommended Fluids and Lubricants
This maintenance section applies to vehicles with a gasoline engine. If the vehicle has a diesel engine, see“Recommended Fluids and Lubricants”
in the Duramax diesel supplement.
Fluids and lubricants identified below by name or specification, including fluids or lubricants not listed here, can be obtained from your dealer.
Usage Fluid/Lubricant
Automatic Transmission DEXRON ULV Automatic Transmission Fluid.
Chassis Lubrication Chassis lubricant meeting requirements of NLGI #2, Category LB or GC-LB.
Engine Coolant 50/50 mixture of clean, drinkable water and use only DEX-COOL coolant. See Cooling System
0 319.
Engine Oil Engine oil meeting the dexos1 specification of the proper SAE viscosity grade. ACDelco dexos1
full synthetic is recommended. See Engine Oil0314.
Front and Rear Axle Driveshaft Splines See your dealer.
Front Axle (Four-Wheel Drive) and Rear Axle See your dealer. Hydraulic Brake System DOT 4 Hydraulic Brake Fluid. See Brake Fluid0326.
Hydraulic Power Steering System GM Power Steering Fluid. See your dealer.
Key Lock Cylinders, Hood Hinges, Body Door Hinge Pins, Tailgate Hinge and Linkage, Fuel Door Hinge, Tailgate Handle Pivot Points, Hinges, Latch Bolt, and Linkage Multi-Purpose Lubricant, Superlube. See your dealer.
Transfer Case (Four-Wheel Drive) DEXRON-VI Automatic Transmission Fluid. Windshield Washer Automotive windshield washer fluid that meets regional freeze protection requirements.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16908340) - 2024 - CRC - 12/7/22
Customer Information 413
vehicle repaired with Genuine GM parts,
even if your insurance coverage does not
pay the full cost.
If another party's insurance company is
paying for the repairs, you are not obligated
to accept a repair valuation based on that
insurance company's collision policy repair
limits, as you have no contractual limits
with that company. In such cases, you can
have control of the repair and parts choices
as long as the cost stays within reasonable
limits.
Publication Ordering Information
Service Manuals
Service manuals have the diagnosis and
repair information on the engine/propulsion,
transmission, axle, suspension, brakes,
electrical system, steering system, body, etc.
Customer Literature
Owner’s manuals are written specifically for
owners and are intended to provide basic
operational information about the vehicle.
The owner’s manual includes the
Maintenance Schedule for all models.Customer literature publications available for
purchase include owner’s manuals, warranty
manuals, and portfolios. Portfolios include an
owner’s manual, warranty manual,
if applicable, and zip lock bag or pouch.
Current and Past Models
Service manuals and customer literature are
available for many GM vehicles.
To check availability and to order,
call 1-800-551-4123 Monday–Friday,
8:00 a.m.–6:00 p.m. Eastern Time
For credit card orders only (VISA,
MasterCard, or Discover), see Helm, Inc. at:
www.helminc.com.
To order by mail, write to:
Helm, Incorporated
Attention: Customer Service
47911 Halyard Drive
Plymouth, MI 48170
Make checks payable in U.S. funds.
Radio Frequency Statement
This vehicle uses license-exempt
transmitters / receivers / systems that
operate on a radio frequency that complies
with Part 15/Part 18 of the Federal
Communications Commission (FCC) rules and
with Innovation, Science and Economic
Development (ISED) Canada's license-exempt
RSS(s) / RSP-100 / ICES-GEN.
Operation is subject to the following two
conditions:
1. The device may not cause harmful interference.
2. The device must accept any interference received, including interference that may
cause undesired operation of the device.
Changes or modifications to any of these
systems by other than an authorized service
facility could void authorization to use this
equipment.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16908340) - 2024 - CRC - 12/7/22
Customer Information 415
Vehicle Data Recording and
Privacy
The vehicle has a number of computers that
record information about the vehicle’s
performance and how it is driven or used.
For example, the vehicle uses computer
modules to monitor and control engine and
transmission performance, to monitor the
conditions for airbag deployment and
deploy them in a crash, and, if equipped, to
provide antilock braking to help the driver
control the vehicle. These modules may
store data to help the dealer technician
service the vehicle or to help GM improve
safety or features. Some modules may also
store data about how the vehicle is
operated, such as rate of fuel consumption
or average speed. These modules may retain
personal preferences, such as radio presets,
seat positions, and temperature settings.
Cybersecurity
GM collects information about the use of
your vehicle including operational and safety
related information. We collect this
information to provide, evaluate, improve,
and troubleshoot our products and services
and to develop new products and services.
The protection of vehicle electronics systems
and customer data from unauthorized
outside electronic access or control is
important to GM. GM maintains appropriate
security standards, practices, guidelines and
controls aimed at defending the vehicle and
the vehicle service ecosystem against
unauthorized electronic access, detecting
possible malicious activity in related
networks, and responding to suspected
cybersecurity incidents in a timely,
coordinated and effective manner. Security
incidents could impact your safety or
compromise your private data. To minimize
security risks, please do not connect your
vehicle electronic systems to unauthorized
devices or connect your vehicle to any
unknown or untrusted networks (such as
Bluetooth, WIFI or similar technology). In
the event you suspect any security incident
impacting your data or the safe operation of
your vehicle, please stop operating your
vehicle and contact your dealer.
Event Data Recorders
This vehicle is equipped with an Event Data
Recorder (EDR). The main purpose of an EDR
is to record, in certain crash or near
crash-like situations, such as an air bag
deployment or hitting a road obstacle, data
that will assist in understanding how a
vehicle’s systems performed. The EDR is
designed to record data related to vehicle
dynamics and safety systems for a short
period of time, typically 30 seconds or less.
The EDR in this vehicle is designed to record
such data as:
.How various systems in your vehicle were
operating;
.Whether or not the driver and passenger
safety belts were buckled/fastened;
.How far (if at all) the driver was
depressing the accelerator and/or brake
pedal; and,
.How fast the vehicle was traveling.
These data can help provide a better
understanding of the circumstances in which
crashes and injuries occur.
Note
EDR data are recorded by your vehicle only
if a non-trivial crash situation occurs; no
data are recorded by the EDR under normal

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16908340) - 2024 - CRC - 12/7/22
Index 425
IndexA
Accessories and Modifications . . . . . . . . . . . 310
Accessory Power . . . . . . . . . . . . . . . . . . . . . . . . . 220
AdaptiveCruise Control . . . . . . . . . . . . . . . . . . . . . . . . . 241
Add-On Electrical Equipment . . . . . . . . . . . . . 306
Adding a Snow Plow or Similar Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306
Additional OnStar Information . . . . . . . . . . . . . . . . . . . . 419
Adjustments Lumbar, Front Seats . . . . . . . . . . . . . . . . . . . . 50
Advanced Driver Assistance Systems . . . . . . . . . . . . . 252
Agreements Trademarks and License . . . . . . . . . . . . . . . 188
Air Cleaner/Filter, Engine . . . . . . . . . . . . . . . . . . 318
Conditioning . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
Filter Life System . . . . . . . . . . . . . . . . . . . . . . . 317
Filter, Passenger Compartment . . . . . . . . 196
Vents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
Air Conditioning . . . . . . . . . . . . . . . . . . . . . . . . . . 191
Airbag System . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
How Does an Airbag Restrain? . . . . . . . . . . 68
Passenger Sensing System . . . . . . . . . . . . . . 69
What Makes an Airbag Inflate? . . . . . . . . . 68 Airbag System (cont'd)
What Will You See after an Airbag
Inflates? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
When Should an Airbag Inflate? . . . . . . . . 67
Where Are the Airbags? . . . . . . . . . . . . . . . . 66
Airbags Adding Equipment to the Vehicle . . . . . . . 73
Passenger Status Indicator . . . . . . . . . . . . . . 121
Readiness Light . . . . . . . . . . . . . . . . . . . . . . . . . 121
Replacing System Parts after a
Crash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Servicing Airbag-Equipped Vehicles . . . . . . 73
Alarm Vehicle Security . . . . . . . . . . . . . . . . . . . . . . . . 32
Alert Lane Change (LCA) . . . . . . . . . . . . . . . . . . . . . 268
Rear Cross Traffic . . . . . . . . . . . . . . . . . . . . . . 263
All-Season Tires . . . . . . . . . . . . . . . . . . . . . . . . . . 345
All-Terrain Tires . . . . . . . . . . . . . . . . . . . . . . . . . . 346
AM-FM Radio . . . . . . . . . . . . . . . . . . . . . . . . 159, 161
Antenna Multi-band . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
Antilock Brake System (ABS) . . . . . . . . . . . . . 233 Warning Light . . . . . . . . . . . . . . . . . . . . . . . . . 125
Appearance Care Exterior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383
Interior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 388
Apple CarPlay and Android Auto . . . . . 177, 179

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16908340) - 2024 - CRC - 12/7/22
426 Index
Assistance Program, Roadside . . . . . . . . . . . . 408
Assistance SystemsAdvanced . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
Automatic EmergencyBraking (AEB) . . . . . . . . . . . . . . . . . . . . . . . . 265
Driving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263
Forward Collision Alert (FCA) System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263
Front Pedestrian Braking (FPB) . . . . . . . . . 266
Lane Change Alert (LCA) . . . . . . . . . . . . . . . 268
Lane Departure Warning (LDW) . . . . . . . . 270
Parking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
Parking and Backing . . . . . . . . . . . . . . . . . . . 253
Rear Cross Traffic Alert (RCTA) . . . . . . . . . 263
Rear Vision Camera (RVC) . . . . . . . . . . . . . . 253
Surround Vision System . . . . . . . . . . . . . . . 254
Audio Bluetooth . . . . . . . . . . . . . . . . . . . . . . . . . 163, 164
Automatic Dimming Mirrors . . . . . . . . . . . . . . . . . . . . . . . 37
Door Locks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Emergency Braking (AEB) DisabledLight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Headlamp System . . . . . . . . . . . . . . . . . . . . . 145
Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
Transmission Fluid . . . . . . . . . . . . . . . . . . . . . . 317
Transmission Shift Lock Control Function Check . . . . . . . . . . . . . . . . . . . . . . . 330 Automatic Transmission
Manual Mode . . . . . . . . . . . . . . . . . . . . . . . . . 226
Auxiliary Roof Mounted Lamp . . . . . . . . . . . . . . . . . . . 148
Avoiding Untrusted Media Devices . . . . . . . 163
Axle Front . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329
Rear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329
B
BatteryExterior Lighting Battery Saver . . . . . . . . 152
Load Management . . . . . . . . . . . . . . . . . . . . . 152
Power Protection . . . . . . . . . . . . . . . . . . . . . . 152
Battery - North America . . . . . . . . . . . . .327, 376
Blade Replacement, Wiper . . . . . . . . . . . . . . . . 331
Blind Spot Mirrors . . . . . . . . . . . . . . . . . . . . . . . . .37
Bluetooth Audio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163, 164
Overview . . . . . . . . . . . . . . . . . . . . . . 170, 171, 174
Brake
Fluid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 326
Pad Life System . . . . . . . . . . . . . . . . . . . . . . . 325
System Warning Light . . . . . . . . . . . . . . . . . 124
Brake Pad Life System . . . . . . . . . . . . . . . . . . . 325
Brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325 Antilock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
Brake Assist . . . . . . . . . . . . . . . . . . . . . . . . . . . 235 Brakes (cont'd)
Electric Parking Brake . . . . . . . . . . . . . . . . . . 234
Braking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 Automatic Emergency (AEB) . . . . . . . . . . . 265
Front Pedestrian (FPB) System . . . . . . . . . 266
Break-In, New Vehicle . . . . . . . . . . . . . . . . . . . . 216
Buckle To Drive . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Bulb Replacement . . . . . . . . . . . . . . . . . . . . . . . . 333 Center High-Mounted Stoplamp(CHMSL) and Cargo Lamp . . . . . . . . . . . . 335
Halogen Bulbs . . . . . . . . . . . . . . . . . . . . . . . . . 333
Headlamp Aiming . . . . . . . . . . . . . . . . . . . . . . 333
Headlamps, Front Turn Signal, Sidemarker, and Parking Lamps . . . . . . 333
License Plate Lamps . . . . . . . . . . . . . . . . . . . 335
Taillamps, Turn Signal, Stoplamps, and Back-up Lamps . . . . . . . . . . . . . . . . . . 334
Buying New Tires . . . . . . . . . . . . . . . . . . . . . . . . 360
C
Calibration Compass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
California Perchlorate Materials Requirements . . . 310
California Proposition 65 Warning . . . . . 1, 376
Camera Rear Vision (RVC) . . . . . . . . . . . . . . . . . . . . . . 253
Truck Bed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16908340) - 2024 - CRC - 12/7/22
428 Index
Data Collection (cont'd)OnStar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 416
Data Recorders, Event . . . . . . . . . . . . . . . . . . . .415
Daytime Running Lamps (DRL) . . . . . . . . . . . .145
Defensive Driving . . . . . . . . . . . . . . . . . . . . . . . . 200
Delayed Locking . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Destination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
Diagnostics Connected Services . . . . . . . . . . . . . . . . . . . . 424
Disabled Vehicle Transporting . . . . . . . . . . . . . . . . . . . . . . . . . . . 379
Distracted
Driving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
Distracted Driving . . . . . . . . . . . . . . . . . . . . . . . . 199
Dome Lamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
Door Ajar Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
Delayed Locking . . . . . . . . . . . . . . . . . . . . . . . . 23
Locks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Power Locks . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Drive Belt Routing, Engine . . . . . . . . . . . . . . . 404
Drive Systems
Four-Wheel Drive . . . . . . . . . . . . . . . . . . . . . . 329
Driver Assistance Systems, Advanced . . . . . . . . . 252
Information Center (DIC) . . . . . . . . . . . 131, 133
Mode Control . . . . . . . . . . . . . . . . . . . . . . . . . . 238
Mode Control Light . . . . . . . . . . . . . . . . . . . . 128 Driver (cont'd)
Teen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
Driving Assistance Systems . . . . . . . . . . . . . . . . . . . . 263
Better Fuel Economy . . . . . . . . . . . . . . . . . . . 199
Characteristics and Towing Tips . . . . . . . . 276
Defensive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
Hill and Mountain Roads . . . . . . . . . . . . . . 207
If the Vehicle is Stuck . . . . . . . . . . . . . . . . . 209
Impaired . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
Loss of Control . . . . . . . . . . . . . . . . . . . . . . . . 202
Off-Road . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
Off-Road Recovery . . . . . . . . . . . . . . . . . . . . . 202
Vehicle Load Limits . . . . . . . . . . . . . . . . . . . . 210
Wet Roads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
Winter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
Dual Automatic Climate Control System . . . . 193
E
E85 or FlexFuel . . . . . . . . . . . . . . . . . . . . . . . . . . 272
ElectricParking Brake . . . . . . . . . . . . . . . . . . . . . . . . . . 234
Parking Brake Light . . . . . . . . . . . . . . . . . . . . 124
Electrical Equipment, Add-On . . . . . . . . . . . . . . . . . . . . 306
System Overload . . . . . . . . . . . . . . . . . . . . . . 335 Electrical System
Engine Compartment Fuse Block . . . . . . . 337
Fuses and Circuit Breakers . . . . . . . . . . . . . 337
Instrument Panel Fuse Block . . . . . . 341, 342
Electronic Stability Control (ESC) Off Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Emergency
OnStar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 418
Engine Air Cleaner/Filter . . . . . . . . . . . . . . . . . . . . . . 318
Air Filter Life System . . . . . . . . . . . . . . . . . . . 317
Check Light (Malfunction Indicator) . . . . 122
Compartment Overview . . . . . . . . . . . . . . . . 313
Coolant Temperature Gauge . . . . . . . . . . . . 118
Coolant Temperature WarningLight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
Cooling System . . . . . . . . . . . . . . . . . . . . . . . . 319
Drive Belt Routing . . . . . . . . . . . . . . . . . . . . . 404
Exhaust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
Fan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323
Heater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
Oil Life System . . . . . . . . . . . . . . . . . . . . . . . . 316
Oil Pressure Gauge . . . . . . . . . . . . . . . . . . . . . 117
Oil Pressure Light . . . . . . . . . . . . . . . . . . . . . . 129
Overheated Protection Operating Mode . . . . . . . . . . . . . . . . . . . . . 323
Overheating . . . . . . . . . . . . . . . . . . . . . . . . . . . 321
Power Messages . . . . . . . . . . . . . . . . . . . . . . . 139