Service Bulletin

Bulletin No.:

20-NA-137

Date:

June, 2020

INFORMATION
Subject:

2021 Chevrolet Suburban, Tahoe, GMC Yukon and Yukon XL New Model Features

Brand:
Chevrolet

Model:

Model Year:
From:

VIN:

To:

From:

To:

Suburban
Tahoe
Yukon
2021

GMC

2021

All

Yukon XL

Involved Countries and Regions

All

Engines:

Transmissions:

5.3L, V8, DI, DFM,
ALUM, GEN 5 —
RPO L84
6.2L, V8, DI, DFM,
ALUM, GEN 5 —
RPO L87
3.0L, L6, DOHC,
TURBO Diesel,
ALUM, CSS50V —
RPO LM2

AUTO 10 SPD,
10L80, ATSS,
ETRS, CPA, GEN
2 — RPO MQC)

North America, Saudi Arabia, Columbia

General Information

5619514

2021 Chevrolet Tahoe
5619513

2021 Suburban

Copyright 2020 General Motors LLC. All Rights Reserved.

Page 2

June, 2020

Bulletin No.: 20-NA-137

and the updated V8 5.3L and 6.2L engines with
dynamic fuel management. All powertrains are
equipped with a standard 10-speed transmission with
push-button electronic shift. These vehicles also
feature an all-new independent rear suspension, an
optional air ride adaptive suspension, and an all-new
power sliding console with a built-in cooler.

Chevrolet Suburban and Tahoe Trim Levels

5619515

2021 GMC Yukon

5627456

2021 GMC Yukon XL
Bulletin Purpose
This purpose of this bulletin is to introduce the
redesigned 2021 Chevrolet Suburban, Chevrolet
Tahoe, GMC Yukon and GMC Yukon XL full-size Sport
Utility Vehicles (SUV’s). The bulletin will help the
Service Department Personnel become familiar with
the engines, transmission, brake system and some of
the other vehicle systems.
Overview
The 2021 Chevrolet Suburban, Tahoe and GMC Yukon
set a new standard for Chevrolet and GMC SUVs by
delivering leading technology and precisely engineered
features. The vehicles offer a broad range of trim levels
and options and three different powertrain
combinations: the all-new 3.0L Duramax turbo-diesel

The 2021 Chevrolet Suburban and Tahoe are now
available in six trim levels.
LS — Entry Level into Chevrolet Large SUV Portfolio
• 5.3L V8 engine, 10-speed transmission
• front bucket seats – cloth
• 8-way power driver seat
• keyless open and start
• remote start
• Wi-Fi
• HD/XM radio
• OnStar®
• foldable second and third row seats
• 18-inch bright silver painted aluminum wheels
• Chevrolet infotainment 3+ system with 10.2-inch
HD color touchscreen
• rain-sensing wipers
• heated power mirrors
• rear park assist
LT — Heart of the Market Entry
• 8-way power passenger seat
• auto-dimming rear view mirror
• Bose® audio system with 9 speakers
• driver memory seat
• hands-free power liftgate with Chevrolet logo light
• leather front bucket seats with heat and auto-temp
• sill plates
• universal home remote
• wireless charging
RST — Expressive Sporty Design Elements with
Street-inspired Character
In addition to, or instead of, the LT features:
• 22-inch ultra-bright machined aluminum wheels
• RST-specific seats
• front and rear black bowties
• unique gloss black sport grille with body-color
surround
• body-color door handles and headlamp accents
• black mirror caps
Z71 — Off–Road Design Elements with Slightly
Enhanced Appearance and Capability
In addition to, or instead of, the RST features:
• 20-inch machined-finish painted wheel
• high approach angle front fascia
• skid plate
• red tow hooks
• unique Z71 assist step

Bulletin No.: 20-NA-137

June, 2020

• 2-speed transfer case
• high capacity air cleaner
• hill descent control
Premier — Focusing on Premium Equipment and
Technology, along with Tailored, Understated Luxury
In addition to, or instead of, Z71 the features:
• 20-inch aluminum wheel
• 8-inch reconfigurable driver information center
• second row power, heated bucket seats
• third row power-folding bench seats
• front and rear park assist
• heated steering wheel with auto-temp
• lane keep assist
• navigation
• power tilt and telescopic steering column
• premium Bose® audio system with 10 speakers
• rear cross traffic alert
• safety alert seat
• side blind zone alert with lane change alert
• vented and perforated front seats
• full-feature, power-folding mirrors
• chrome door handles w/ body-color strip
• dual exhaust (with gas engine)
• magnetic ride control chassis
• 2-speed transfer case
• hill descent control
High Country — Outdoors Top Level Model
Customized with Premium Features
In addition to, or instead of, the Premier features:
• 22-inch polished aluminum wheels with bronze
inserts
• head-up display
• digital rear view mirror
• 360-degree camera
• rear camera washer
• rear pedestrian detection

GMC Yukon Trim Levels
2021 GMC Yukon features four trim levels:
SLE — Low Volume Entry Point to the Yukon family
• 5.3L V8 engine, 10-speed transmission
• electronic transmission range selector
• front bucket seats – cloth
• keyless open and start
• remote start
• Wi-Fi
• HD/XM Radio
• OnStar®
• wireless phone projection
• 18-inch painted wheels
• single exhaust
• fog lamps
• Light Emitting Diode (LED) headlamps/taillamps

Page 3

• manual rear liftgate
• IntelliBeam
• forward collision alert
• following gap indicator/sensor
• pedestrian detection – front
• front and rear park assist
• low speed auto braking
• HD rear vision
SLT — GMC Refinement for the Mainstream Market
In addition to, or instead of, the SLE features:
• front bucket seats – leather
• front heated seats, vented
• perforated front seats
• power passenger seat 8-way
• memory seat, driver
• wireless charging
• Bose® audio (9-speakers
• universal home remote
• auto-dimming rear view mirror
• 20-inch polished wheels
• sill plates
• hands-free power liftgate with GMC logo light
• safety alert seat
• side blind zone with lane change alert
• rear cross traffic alert
• lane keep assist
AT4 — Premium Capability
In addition to, or instead of, the SLT features:
• magnetic ride control
• 2-speed transfer case ‒ 4-Wheel Drive (4WD)
• hill descent control ‒ 4WD
• front high approach angle
• AT4-specific seats
• heated steering wheel
• memory package
• second row power release bench
• third row power folding bench
• second row heated seats
• heated and vented front seats
• full feature outside rear view mirror
• perforated front seats
• 20-inch machined mid-paint wheels
• 20-inch all terrain tires
• torch red tow hooks
• skid plate
• AT4 front door sill plates
Denali — Ultimate Expression of Professional grade
In addition to, or instead of, the AT4 features:
• 6.2L V8
• 10-speed transmission
• magnetic ride control
• 2-speed transfer case ‒ 4WD

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June, 2020

hill descent control ‒ 4WD
Denali-exclusive interior and instrument panel
heated steering wheel
memory package
second row heated seats
second row power release buckets
third row power folding bench
15-inch multicolor head up display
navigation
Bose® performance series audio (14 speakers)
20-inch polished aluminum wheels
dual exhaust (with gas engine)
power-fold full feature mirrors
HD surround vision
rear pedestrian detection

Exterior Features
Steel/Aluminum Structure
The 2021 Chevrolet Suburban, Tahoe and GMC Yukon
exterior features include a new, thicker steel frame, a
lighter frame body, and aluminum closures. The
structure uses a mix of materials including advanced
high strength steel, high strength steel, steel, and
aluminum.

Bulletin No.: 20-NA-137

The power panoramic sunroof system operates only
when the ignition is turned to the RUN or Accessory
positions; this allows for retained accessory power
control of the sunroof and sunshade through the BCM.
Once the ignition switch is turned to OFF, the sunroof
and sunshade continue to operate until any door is
opened or when the retained accessory power
times out.
The sunroof and sunroof shade switch assembly
contain two rocker-type switches that are used to
control the sunroof.

Performance Features
Independent Rear Suspension
The all-new standard independent rear suspension has
many advantages over the previous models. It creates
a smoother ride and increases handling dynamics due
to the independent wheel motion and optimized rear
suspension geometry. The independent rear
suspension also enables a more natural seating
position for passengers in the third row, creating a more
comfortable seating experience, particularly for adults,
as well as greater cargo area and volume.
Air Ride Adaptive Suspension
Note: The vehicle will not lower when exiting if the
level switch is in Off-road, or tow-haul/trailering mode.
The 2021 Tahoe and Yukon feature an all-new,
first-in-class, active automatic level control suspension.
The air suspension improves ground clearance for
off-road driving conditions. The variable-rate air springs
allow a driver selectable ride height. While engaged,
the Yukon AT4 can be raised 25.4 mm (1 in) in
increased ground clearance mode or 50.8 mm (2 in)
when maximum ground clearance mode is selected.
The underside offers skid plates for chassis and
suspension component protection from road debris.

Panoramic Sunroof

Interior Features

5619516

The 2021 Tahoe and Yukon feature an all-new
panoramic power sunroof that allows for greater light
and a sense of openness in the cabin. The panoramic
sunroof also includes a power sunscreen shade cover.

Interior Volume
The Suburban/Tahoe/Yukon length has been stretched
to increase rear seat room. In addition, the SUVs are
slightly wider and taller as compared to previous
models. The independent rear suspension architectural
change enables a natural seating position for
passengers in the third row. Short wheelbase models
now have more cargo volume behind second and third
row seating areas. The third row leg room increases by
254 mm (10 in) and cargo space increases 66% over
the previous generation vehicles.

Bulletin No.: 20-NA-137

June, 2020

Page 5

Brakes Systems
Brake System Overview
The 2021 Chevrolet Suburban, Tahoe and GMC Yukon
feature an integrated brake control system, including an
electro-hydraulic boost system that replaces the
conventional vacuum-based power assist brake
system. The electro-hydraulic brake system supplies
on-demand power when the driver presses the brake
pedal. The 2021 Chevrolet Suburban, Tahoe and GMC
Yukon feature 4-wheel, 17-inch disc brake rotors as
standard equipment. The brakes are equipped with a
new brake pad lining wear sensor system and an
electronic parking brake system.

Antilock Braking System

5619517

1. 254 mm (10 in) Additional Third Row Legroom
2. 66% Additional Cargo Space Behind Third Row
Seating
2021 Tahoe Leg and Cargo Room
Multicolor Head-Up Display

The Antilock Braking System (ABS) is equipped with
the integrated brake control system. Integrated brake
control relies upon an electromechanical device that
includes a brake system control module. The module
interprets and converts driver input and provides a
corresponding hydraulic pressure output to activate a
standard brake system according to the driver’s
demand. In an event of no electrical energy or failure
condition, the driver’s input is mechanically converted
to a hydraulic pressure output.
Compared to conventional brake apply systems, the
integrated brake control enables additional brake
pressure and provides additional brake system
features.
Antilock Braking System Components
The following vehicle systems and components work in
conjunction with integrated brake control:
Body Control Module
The Body Control Module (BCM) monitors the brake
pedal position sensor signal when the brake pedal is
applied. Then the BCM sends a high-speed serial data
message to the brake system control module,
indicating the brake pedal position.

5619518

A new, available multicolor head-up display projects
key, customizable vehicle data on the windshield in a
76.2 by 177.8 mm (3 by 7 in) display to help drivers
keep their eyes on the road.
Power Sliding Console
The 2021 Tahoe and Yukon features the first-ever
optional power sliding center console in the large SUV
market. The center console can slide backwards up to
254 mm (10 in) to enhance overall storage flexibility
and organization. A power rocker switch in the center
overhead console operates the power slide
functionality. In addition, there is a hidden storage
drawer that can secured valuables when in valet mode.

Instrument Cluster
The instrument cluster displays the vehicle speed
based on the information from the Engine Control
Module (ECM). The ECM communicates the vehicle
speed information via a high speed serial data
message to the BCM. The BCM then communicates
the vehicle speed information via a low speed serial
data message to the instrument cluster. Speed is
displayed in kilometers per hour (km/h) or miles per
hour (MPH), based on the vehicle settings.
Multi-axis Acceleration Sensor
The yaw rate, lateral acceleration, and longitudinal
acceleration sensors are combined into one multi-axis
acceleration sensor, internal to the inflatable restraint
sensing and diagnostic module. The brake system
control module receives yaw rate, lateral acceleration,
and longitudinal acceleration inputs from the multi-axis
acceleration sensor via serial data. The module
activates stability control and the hill hold start assist
function depending on multi-axis acceleration sensor
input.

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June, 2020

Traction Control Multifunction Switch

Bulletin No.: 20-NA-137

module. Therefore, a power-up self-test is performed to
verify correct operation of system components. The
brake system control module performs the first phase of
the power-up self-test when the ignition is first turned
ON. This phase consists of internal self-testing of the
brake system control module along with electrical
checks of system sensors and circuits.
Disconnecting the 12V battery is the only method that
ensures a self-test will not occur while servicing the
brakes. The self-test consists of an internal hydraulic
test of the brake master cylinder and an external
hydraulic leak test of the brake lines and calipers. The
self-test pressurizes all four circuits leading to the
calipers.

Antilock Brake System Performance
Enhancement Systems

5619519

The BCM monitors the signal circuit from the traction
control multifunction switch (shown circled above). The
BCM communicates a high speed serial data message
to the brake system control module, indicating the
switch position. The traction control and stability control
are manually disabled or enabled by pressing the
traction multifunction control switch.
Steering Wheel Angle Sensor
The brake system control module receives serial data
message inputs from the steering angle sensor.
Steering wheel rotation speed and direction are
calculated to determine the intended driving direction
and any abrupt or evasive maneuvers. The steering
wheel angle sensor is an internal component of the
power steering gear.
Transmission Control Module
The brake system control module receives high speed
serial data message inputs from the transmission
control module, indicating the gear position of the
transmission for hill start assist or hill hold functions.
Wheel Speed Sensors
Unique directional wheel speed sensors can detect
wheel direction as well as zero wheel speed. The wheel
speed sensors receive a 12 volt power supply voltage
from the brake system control module and provide an
output signal to the module. As the wheel spins, the
wheel speed sensor sends the brake system control
module a direct current (DC) square wave signal. The
brake system control module uses the frequency of the
square wave signal to calculate the wheel speed.

Power-Up self-Test
The brake system control module is able to detect
many malfunctions whenever the ignition is ON.
However, certain failures cannot be detected unless
active diagnostic tests are performed on the
components. Shorted solenoid coil or motor windings,
for example, cannot be detected until the components
are commanded ON by the brake system control

Depending on options, the following ABS performance
enhancement systems may be provided:
• brake assist features
– panic brake assist
– hydraulic fade compensation
– rear brake boost
– electronic pre-fill
– motor-on-caliper torque overlay
• electronic stability control features
– roll over mitigation/pre-emptive electronic stability
control
– torque vectoring by brakes
– flat tire electronic stability enable
– electronic stability control with vehicle weight
estimation
• traction control
– vehicle stuck control
– power hop control
– engine drag control
– enhanced off-road control
• integrated brake control system
– brake drying/cleaning
– hill start assist
– driveline damping
– extended hill hold start assist