21NA128

Service Bulletin
Bulletin No.:
21-NA-128
Date:
June, 2021
TECHNICAL
Subject:
MIL Illuminated- ECM Update for P026C, P20EE, or P11D5
Brand:
Model:
from
to
Model Year:
Chevrolet
Silverado
2500HD/
3500HD
2021
GMC
Sierra
2500HD/
3500HD
2021
VIN:
Transmission:
2021
Before
1GC4YTEY5MF261413
Involved Region or Country
2021
Engine:
from
to
Equipped with
6.6L Engine
(RPO L5P
Equipped with
6.6L Engine
(RPO L5P
North America. Israel, Palestine, Middle East, Australia and New Zealand.
Additional Options (RPOs)
Condition
Some customers may comment that the MIL is illuminated.
Some technicians may find DTC P026C, P20EE, or P11D5
Cause
The cause of the condition may be a software anomaly
Correction
Please check for any open campaigns and perform as necessary:
• If campaign N212336570 or campaign N212331790 applies to this VIN and is open,
please close the campaign. Doing this will install the latest ECM update that includes
P20EE, P026C, and P11D5 enhancements.
• If the campaign is not released for this VIN or if the campaign is already closed,
please check for an ECM update.
Reprogram the Engine Control Module (ECM).
Service Procedure
Caution: Before downloading the update files, be sure
the computer is connected to the internet through a
network cable (hardwired). DO NOT DOWNLOAD or
install the files wirelessly. If there is an interruption
during programming, programming failure or control
module damage may occur.
• Ensure the programming tool is equipped with the
latest software and is securely connected to the
data link connector. If there is an interruption
during programming, programming failure or
control module damage may occur.
• Stable battery voltage is critical during
programming. Any fluctuation, spiking, over
voltage or loss of voltage will interrupt
programming. Install a GM Authorized
Copyright 2021 General Motors LLC. All Rights Reserved.
Programming Support Tool to maintain system
voltage. Refer to www.gmdesolutions.com for
further information. If not available, connect a fully
charged 12 V jumper or booster pack
disconnected from the AC voltage supply. DO
NOT connect a battery charger.
• Follow the on-screen prompts regarding ignition
power mode, but ensure that anything that drains
excessive power (exterior lights, HVAC blower
motor, etc) is off
• Clear DTCs after programming is complete.
Clearing powertrain DTCs will set the Inspection/
Maintenance (I/M) system status indicators to NO.
Caution: Be sure the VIN selected in the drop down
menu (1) is the same as the vehicle connected (2)
before beginning programming.
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Important: Techline Connect and TIS2WEB screens
shown above.
Important: If the same calibration/software warning is
noted on the TLC or SPS Summary screen, select OK
and follow screen instructions. After a successful
programming event, the WCC is located in the Service
Programming System dialogue box of the SPS
Summary screen. No further action is required. Refer to
the Warranty section of the bulletin.
1. Reprogram the Engine Control Module. Refer to
K20 Engine Control Module: Programming and
Setup in SI.
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Page 5
Note: The screenshots above are an example of
module programming and may not be indicative of the
specific module that is being programmed. Module
selection and VIN information have been blacked out.
Important: To avoid warranty transaction rejections,
you MUST record the warranty claim code provided on
the SPS Warranty Claim Code (WCC) screen shown
above on the job card. Refer to callout 1 above for the
location of the WCC on the SPS screen
2. Record SPS Warranty Claim Code on job card for
warranty transaction submission.
Warranty Information
For vehicles repaired under the Emission coverage,
use the following labor operation. Reference the
Applicable Warranties section of Investigate Vehicle
History (IVH) for coverage information. 2 years/24,000
miles Federally and 3 years/50,000 miles in California.
Labor Operation
Description
Labor Time
*2887368
P026C/P20EE ECM Reprogramming Update
0.3 hr
*This is a unique Labor Operation for Bulletin use only.
Important: **To avoid warranty transaction rejections, carefully read and follow the instructions below:
• The Warranty Claim Code must be accurately entered in the “SPS Warranty Claim Code” field of the transaction.
• When more than one Warranty Claim Code is generated for a programming event, it is required to document all Warranty
Claim Codes in the “Correction” field on the job card. Dealers must also enter one of the codes in the “SPS Warranty Claim
Code” field of the transaction, otherwise the transaction will reject. It is best practice to enter the FINAL code provided by
SPS/SPS2.
Warranty Claim Code Information Retrieval
If the SPS Warranty Claim Code was not recorded on
the Job Card, the code can be retrieved in the SPS
system as follows:
1. Open TLC/TIS on the computer used to program
the vehicle.
2. Select and start SPS/SPS2.
3. Select Settings.
4. Select the Warranty Claim Code tab.
The VIN, Warranty Claim Code and Date/Time will be
listed on a roster of recent programming events. If the
code is retrievable, dealers should resubmit the
transaction making sure to include the code in the SPS
Warranty Claim Code field.
Version
Modified
1
Released May 28, 2021
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.
WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION
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.
WE SUPPORT VOLUNTARY
TECHNICIAN
CERTIFICATION