Bulletin No.:

Service Bulletin

Date:

20-NA-167
September, 2020

TECHNICAL
Subject:

Malfunction Indicator Lamp (MIL) Illuminated - DTC P0128 Set
This bulletin replaces PIP5685. Please discard PIP5685.

Brand:

Model:

Chevrolet

Silverado 1500 (New
Model)

GMC

Sierra 1500 (New
Model)

Model Year:

VIN:

from

to

from

to

2019

2020

-

-

Engine:

Transmission:

LV3

-

Involved Region or Country

North America

Condition

Some customers may comment that the MIL is illuminated.
Some technicians may find DTC P0128 (Engine Coolant Temperature (ECT) Below
Thermostat Regulating Temperature) set in the Engine Control Module (ECM).

Cause

This condition may be caused by the P0128 diagnostic running at the incorrect time
which can cause a false failure and the DTC to set.

Correction

If a vehicle comes in with this concern, it will be necessary to reprogram the ECM with the
latest calibration.
– An updated ECM calibration was released to update the ECT “Engine Coolant
Temperature” diagnostic. Once the updated calibration is installed, operate vehicle and
verify DTC does not return. Do not replace the thermostat or any other components for
this condition unless SI diagnostic lead to a component or electrical circuit fault.

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.
Note: Carefully read and follow the instructions below.
•

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.

•

•

Copyright 2020 General Motors LLC. All Rights Reserved.

Stable battery voltage is critical during
programming. Any fluctuation, spiking, over
voltage or loss of voltage will interrupt
programming. Install a GM Authorized
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.
Turn OFF or disable systems that may put a load
on the vehicles battery such as; interior lights,
exterior lights (including daytime running lights),
HVAC, radio, etc.
Clear DTCs after programming is complete.
Clearing powertrain DTCs will set the Inspection/
Maintenance (I/M) system status indicators to NO.

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September, 2020

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5431207

Bulletin No.: 20-NA-167

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Page 3

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.
Important: When programming a module in GM’s new
Vehicle Intelligence Platform, or VIP, the power mode
(ignition) needs to be off or errors may occur. This
involves the 2020 Chevrolet Corvette, Cadillac CT5 and
CT4, as well as the upcoming full-size Chevrolet, GMC,
Cadillac SUVs and Buick Envision. Serial Data
Message Authentication also needs to have the
ignition off.
1. Reprogram the ECM module. Refer to K20 Engine
Control Module: Programming and Setup in SI.
Modify as required (e.g., select x module from the
controller screen. Then provide step-by-step
instructions or refer to SI procedure.

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September, 2020

Bulletin No.: 20-NA-167

5431209

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.

Parts Information
No parts are required for this repair.

Warranty Information
For vehicles repaired under warranty, use:
Labor Operation

Description

Labor Time

2810075

Engine Control Module Reprogramming with SPS

Use Published Labor
Operation Time

*This is a unique Labor Operation for Bulletin use only.
Important: **To avoid warranty transaction rejections, carefully read and follow the instructions below:
• The SPS 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.

Bulletin No.: 20-NA-167

September, 2020

Page 5

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 TIS on the computer used to program the
vehicle.
2. Select and start SPS.
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

1

Modified

Released August 26, 2020

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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