20NA055

Bulletin No.:
Service Bulletin
Date:
20-NA-055
September, 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:
ATS
Cadillac
Chevrolet
from
to
2018
2019
Date
Breakpoint:
Engine:
Transmission:
All
All
LF4
MG9, M5U
L86
All
2WD/4WD:
Escalade
2018
2020
All
SOP - Jan.
8,2020
CTS
2018
2019
All
All
LF3, LT4
MGG, M5U
Camaro
2018
2020
All
All
LT1, LT4
M12, M14,
MM6, M5U,
MJK,
MH3, MGL
Express
2020
2020
All
LV1
All
2018
2018
All
L83, L86, LV3
All
2018
2018
4WD
L86
M5U
Silverado LD
2019
2019
All
L83, LV3
All
Suburban
2018
2020
All
L83, L86
All
Tahoe
2018
2020
All
L83, L86
All
Savana
2020
2020
All
LV1
All
2018
2018
All
L83, L86, LV3
All
2018
2018
4WD
L86
M5U
Sierra
Limited
2019
2019
All
L83, LV3
All
Yukon
2018
2020
All
L83, L86
All
Silverado
Sierra
GMC
Model Year:
All
SOP - Jan.
8,2020
All
SOP - Jan.
8,2020
Involved Region or Country
North America, Middle East, Israel, Chile, Colombia, Ecuador, Paraguay, Peru, Uruguay,
Thailand
Condition
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
Copyright 2020 General Motors LLC. All Rights Reserved.
Page 2
September, 2020
Bulletin No.: 20-NA-055
• 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.
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.
•
•
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
September, 2020
Page 3
5644477
5431207
Page 4
September, 2020
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 Information section of this bulletin.
Bulletin No.: 20-NA-055
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 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.
5644478
Bulletin No.: 20-NA-055
September, 2020
Page 5
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 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/SPS2.
Page 6
September, 2020
Bulletin No.: 20-NA-055
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
5
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.
September 18, 2020 – Added the Cadillac ATS, CTS and Chevrolet Camaro to Model
section and updated the programming template.
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