Bulletin No.:

Service Bulletin

Date:

20-NA-055
August, 2020

TECHNICAL
Subject:

Instrument Panel Cluster (IPC) Gauges Inoperative, Numerous Driver information
Center (DIC) Error Messages, No Brake or Electric Power Steering Assist,
Transmission in Default Gear, No Reverse and/or Back Up Lights, No Daytime Running
Lights (DRL), No Cruise or Adaptive Cruise and/or No Trailer Brake Lights

Attention: This bulletin is ONLY applicable to the Models / Model Years equipped with the RPOs
noted in the table below.

Brand:

Model:

Cadillac

Date
Breakpoint:

Engine:

Transmission:

2020

All

SOP - Jan.
8,2020

L86

All

2020

2020

All

LV1

All

2018

2018

All

L83, L86, LV3

All

Escalade

2018

Express

2018

2018

4WD

Silverado LD

2019

2019

All

Suburban

2018

2020

All

Tahoe

2018

2020

All

Savana

2020

2020

All

2018

2018

All

Sierra
GMC

2WD/4WD:

to

Silverado
Chevrolet

Model Year:
from

2018

2018

4WD

Sierra
Limited

2019

2019

All

Yukon

2018

2020

All

Copyright 2020 General Motors LLC. All Rights Reserved.

All

SOP - Jan.
8,2020

All

SOP - Jan.
8,2020

L86

M5U

L83, LV3

All

L83, L86

All

L83, L86

All

LV1

All

L83, L86, LV3

All

L86

M5U

L83, LV3

All

L83, L86

All

Page 2
Involved Region or Country

Condition

August, 2020

Bulletin No.: 20-NA-055

North America, Middle East, Israel, Chile, Colombia, Ecuador, Paraguay, Peru, Uruguay,
Thailand
Some customers may comment on one or more of the following two fault conditions:
1. Aborted Crank:
– Vehicle begins to crank, stops cranking and then has a successful start
2. CAN Lockup:
• IPC gauges inoperative
• Numerous DIC error messages
• Oil pressure gauge reads zero
• Coolant temperature gauge reads zero
• Speedometer gauge reads zero
• Tachometer gauge reads zero
• Fuel gauge reads zero
• Engine appears to be operating in a reduce power mode
• No brake assist
• Possible no electric power steering assist
• Transmission in default gear
• Battery gauges are correct
• No reverse gear and/or no back-up lights
• DRL inoperative
• Numerous DIC error messages displayed
Note: Headlights can be manually turned On.
• Auto headlights inoperative
• The center-stack and radio will be operational
• When the engine is stopped and the HSLAN bus goes to sleep, fault condition is
cleared.
Some customers may also comment that the vehicle begins to crank, stops cranking and
then has a successful start.
Note: U0100 alone is not a good indication of this issue. A better indication of the
condition are the symptoms listed above.
If the vehicle is left in this condition for an extended period, some technicians may find
U0100 (Lost Communication With Engine Control Module) set.
Some technicians may also find when the engine is stopped and the HSLAN bus goes to
sleep, the fault condition is cleared.

Cause

This condition may be caused by a software anomaly.

Correction

If you encounter a vehicle with any of the above conditions, reprogram the Engine Control
Module (ECM) with the latest available software.

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.
Important: 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.

•

•

•

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 12V 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.

Bulletin No.: 20-NA-055

August, 2020

Page 3

5431207

Important: TIS2WEB screen shown. Techline Connect
screen is similar and will be included soon.
Important: If the Same Calibration/Software Warning
is noted on the SPS 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
Information section of this bulletin.
1. Reprogram the Engine Control Module (ECM).
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.

Page 4

August, 2020

Bulletin No.: 20-NA-055

5431209

Important: TIS2WEB screen shown. Techline Connect
screen is similar and will be included soon.
Important: To avoid warranty transaction rejections,
you MUST record the warranty claim code provided on
the SPS Warranty Claim Code (WCC) screen on the
job card. Refer to callout 1 above for the location of the
WCC on the SPS screen.
2. Record the SPS Warranty Claim Code on the job
card for warranty transaction submission.

Parts Information
No parts are required for this repair.

Warranty Information
Federal Select Component Emission Warranty
coverage code E2 applies for this module programming
event. This reprogramming is covered for 8 years/
80,000 miles (U.S.) or 8 years/130,000 km (Canada).
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.
Labor
Operation

Description

Labor Time

2886718*

Engine Control Module
Reprogramming with SPS
for Loss of Communication
to ECM

0.5 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 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-055

August, 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

4

Modified

Released May 04, 2020
June 10, 2020 – Updated the Condition section.
July 10, 2020 – Updated the Models section.
August 03, 2020 – Added the Express and Savana models, added the 2020 Model Year
to certain vehicles and added Date Breakpoints to the Model section.

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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