Bulletin No.:

Service Bulletin

Date:

20-NA-090
August, 2023

INFORMATION
Subject:

Identifying Non-GM ECM Calibration Use and Power-up Hardware Detection in
Duramax Diesel Engines Using GDS 2

Attention: In order to process an engine/transmission/drivetrain hard part Warranty Transaction,
the Service Personnel must retrieve and save the required GDS 2 screen shot
information as outlined below for the specific vehicle, before disassembly or removing
the engine/transmission/drivetrain components from the vehicle. Always refer to the
GM Service Policy and Procedures Manual for the latest GM Policy and Procedures
Information.
Brand:

Model:

Cadillac

Chevrolet

VIN:

to

Escalade Models

2021

2024

Silverado 1500

2020

2021

Silverado 1500 New
(RPO J22, VIN Digit
5 = A / D)

2022

2022

Silverado 1500

2023

LZO

Silverado 2500HD/
3500HD

2020

LM2, L5P

Silverado 4500HD,
5500HD and
/6500HD

2019

Tahoe

to

2024

L5D
—

—

—

2021

Sierra 1500

2020

2021

2022

2022

Sierra 1500

2023

Sierra 2500HD/
3500HD

2020

Yukon Models

2021

Copyright 2023 General Motors LLC. All Rights Reserved.

Transmission:

LM2

Sierra 1500 New
(RPO J22, VIN Digit
5 = H / U)

Involved Region or Country

from

Engine:

from

Suburban

GMC

Model Year:

LM2

LZO
2024

North America, Israel, Australia, New Zealand, Europe

LM2, L5P
LM2

Page 2

August, 2023

Bulletin No.: 20-NA-090

Information

GDS2 Software Updates and Screen Views

Important: Service agents must comply with all
International, Federal, State, Provincial, and/or
Local laws applicable to the activities it performs
under this bulletin, including but not limited to
handling, deploying, preparing, classifying,
packaging, marking, labeling, and shipping
dangerous goods. In the event of a conflict between
the procedures set forth in this bulletin and the
laws that apply to your dealership, you must follow
those applicable laws.

GDS 2 Software updates are available when released
and are indicated by the following prompt: Diagnostic
Package Updates Available. Whenever this prompt is
displayed, press the Update (1) button to download the
latest available software version.
Typical GDS 2 screen views may vary due to Model
Year, Model, Engine, Transmission, and other
Equipment, and for example if the view was saved as a
“Report” or as a single screen shot .jpg, .jpeg or .png
file. It also depends on the GDS 2 software version
currently being used by the Service Technician.
Notice: BEFORE authorizing any Duramax® diesel
engine or transmission replacement, the Calibration
Group will require copies of both of the following GDS 2
screens in the .jpg, .jpeg or .png file format:

General Motors Position on Aftermarket
Power-Up Devices
General Motors does not support or endorse the use of
devices or modifications that when installed, increase
the engine horsepower and torque.
This bulletin outlines the procedures to identify the
presence of non-GM (aftermarket) calibrations. GM
recommends performing this check whenever a hard
part failure is seen on internal engine, transmission,
transfer case or rear axle components, and before
disassembly, repair or replacement of an engine,
transmission, transfer case or rear axle assembly under
warranty. It is also recommended that the engine
calibration verification procedure be performed
whenever diagnostics indicate that an exhaust after
treatment system component replacement is
necessary.
Various Symptoms Caused by an Aftermarket
Power-Up Kit or Hardware
• Poor performance
• Drivability concerns
• Increased emissions
• Knocking noise
• Engine damage
• Smoke from exhaust

Engine Control Module - Calibration History
Screen
•

Navigate to:
⇒ Module Diagnostics
⇒ Engine Control Module
⇒ Identification Information
⇒ Calibration History
• On this screen, you should see:
⇒ Calibration History Buffer
⇒ Number of Calibration History events stored
⇒ Calibration Part Number History
⇒ Calibration Verification Number History
⇒ Engine Calibration Part Number History X
Counter

Bulletin No.: 20-NA-090

August, 2023

Page 3

4749840

Capture a photo of the Calibration History screen, verify
all of the data listed above is on the photo as well as the
VIN at the bottom of the screen.
• It may be required to scroll the screen and take
multiple photos to capture all of the calibration
history events. Save photo(s) and attach it to the
email.
Note: Repeated “FFFF”s or “0000”s are harmless.
They are place holders, and are not actual calibrations.
It is not necessary to photograph extra screens
containing only this type of calibration (FFFF’s or
0000’s).
Another option is to select the Create Report button in
the upper right of the screen. Save the report and
attach it to the E-mail.
Notice: This is a typical GDS 2 report generated by
selecting the “Create Report” button, and taken from a
Model Year 2017 Silverado showing the VIN,
Calibration History, Calibration Verification Number
History and other Associated Parameters

Engine Control Module - Engine Overspeed
Event Data
•

Navigate to:
⇒ Module Diagnostics
⇒ Engine Control Module
⇒ Event Information

⇒ Engine Overspeed Event data
• On this screen, you should see:
⇒ Engine Overspeed Counter
⇒ Total Engine Overspeed Time
⇒ Odometer When Engine Overspeed Detected
⇒ Engine Speed When Engine Overspeed
Detected
⇒ Current Gear When Engine Overspeed
Detected
⇒ Engine Speed When Engine Overspeed
Detected
⇒ Current Gear When Engine Overspeed
Detected
⇒ Vehicle Speed When Engine Overspeed
Detected
⇒ Accelerator Pedal Position When Engine
Overspeed Detected
⇒ MAF When Engine Overspeed Detected

Page 4

August, 2023

Bulletin No.: 20-NA-090

5591397

Capture a photo of the Data Display screen, verify all of
the data listed above is on the photo as well as the VIN
at the bottom of the screen.
⇒ Save photo and attach it to E-mail.
Another option is to select the Create Report button in
the upper right of the screen. Save the report and
attach it to the E-mail.
Notice: This is a typical GDS 2 report generated by
selecting the “Create Report” button, and taken from a
Model Year 2020 Silverado showing the: VIN and
Engine Overspeed Event Data.

Aftermarket Equipment installed in the vehicle
Notice: If you notice any aftermarket equipment or
devices, please take a photo of the device and
document the brand, model, and model number. Please
send this information in with the documents requested.
Instructions for E-Mailing the Required Information
and .jpg, .jpeg or .png Files to the Calibration Group
1. E-mail copies of the files to [email protected]
Note: Properly providing the requested information in
Step 2 and Step 3 is extremely important.
2. In the Subject line of the E-mail include the phrase
”Duramax® diesel”, the complete VIN and Service
Agent BAC.
Important: DO NOT cut and paste the GDS 2 screen
shots into the body of the e-mail. The .jpg, .jpeg or .png
files must be sent as e-mail ATTACHMENTS.

3. In the Body of the E-mail include the following:
3.1. Complete VIN
3.2. Mileage
3.3. Job Card Number (R.O. Number)
3.4. Service Agent BAC.
3.5. Service Personnel Name (Manager or
Technician)
3.6. A complete and comprehensive description of
the customer concern and cause of the
concern.
3.7. Include any additional information as to why
the Service Personnel believes that there
may be aftermarket calibrations or hardware
installed on the vehicle.
4. When sending the e-mail to the Calibration Group,
the .jpg, .jpeg or .png files must be “attached” to
the e-mail, in order to properly validate the
calibration.
5. E-mails that are sent without all of the above
information and attachments as outlined, may be
returned to the sender with a request for the
missing information.
6. Remember to review e-mail replies for further
information from the Calibration Group.

Bulletin No.: 20-NA-090

August, 2023

Page 5

7. The Service Agent will receive an e-mail reply from
the Calibration Group after the calibrations have
been validated. The e-mail reply will advise the
Service Agent if the calibrations are OEM.
8. The Service Personnel may call the PQC after
receiving their e-mail notification from the
Calibration Group informing them that the
calibrations are OEM, if required to do so for
Warranty Requirements. Be prepared to provide all
of the usual documentation that is normally
required when requesting an assembly
authorization from the PQC.
• If the Calibration Group determines that the
calibrations ARE aftermarket calibrations, DO
NOT contact GM Technical Assistance to
discuss warranty concerns on the aftermarket
calibrations. All questions and concerns about
warranty should be directed to the Service
Agent’s District Manager Aftersales (DMA) in
the United States and in Canada to the District
Manager - District Service Manager (DSM).

Warranty Information
•
•

•
•

The Service Management must be involved in any
situation that would justify the use of labor
operation 0600014.
Notify the Service Agent’s District Manager
Aftersales (DMA) in the United States and in
Canada the District Manager - District Service
Manager (DSM).
All claims will have to be routed to the Warranty
Support Center (WSC) for approval.
Please refer to the latest version of Corporate
Bulletin Number 09-00-89-016, Labor Operation
0600014 - Suspected Tampering or Vehicle
Modifications for important information.

Labor
Operation

Description

Labor Time

0600014*

Suspected Tampering or
Vehicle Modifications

0.2 hr

*This is a unique Labor Operation for Bulletin use only.

Version

6

Modified

Released May 04, 2020
Revised November 17, 2020 — Added 2021 Model Years
Revised January 14, 2022 — Added the 2022 Model Year and Australia/New Zealand.
Revised January 24, 2022 – Added Escalade Models, Silverado 1500, Suburban, Tahoe
Sierra 1500 and Yukon Models also added RPO LM2.
Revised September 09, 2022 – Added the 2023 Model Year
Revised July 31, 2023 - Added 2024 Model Year.

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these
technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper
service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a
job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your
vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the
information.

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