20NA191

Bulletin No.:
Service Bulletin
Date:
20-NA-191
September, 2020
TECHNICAL
Subject:
Brand:
Cadillac
Auto Start/Stop Disabled with Malfunction Indicator Lamp (MIL) Illuminated and DTC
U0599 Set
Model:
CT4
CT5
Model Year:
VIN:
from
to
from
to
2020
2020
—
—
Engine:
Transmission:
—
—
Involved Region or Country
North America, Cadillac Korea, Middle East
Additional Options (RPOs)
Equipped with Auto Start/Stop (RPO KL9)
Condition
Some customers may comment on the Auto Start/Stop being inoperative with the
Malfunction Indicator Lamp (MIL) illuminated.
If battery voltage stays >11V during the cold crank, the ECM will set DTC U0599: Auto
Start/Stop disabled. The ECM will disable Auto Start/Stop upon first failure of the DTC
and NOT illuminate a MIL (design intent). Auto Start/Stop will be disabled and the MIL will
illuminate on the second consecutive failure.
After 4 key cycles, the MIL will clear and Auto Start/Stop will resume, that diagnostic runs
without failure.
Cause
The cause of the condition may be a software anomaly in the Engine Control Module
(ECM). A DC/DC mis-calculation of the CAN protection value when Boost Enable =
FALSE and Crank = TRUE.
Correction
Reprogram the 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.
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
Copyright 2020 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 12V jumper or booster pack disconnected
from the AC voltage supply. DO NOT connect a
battery charger.
Ensure the ignition is turned OFF, load on the
vehicle’s battery such as; interior lights, exterior
lights (including daytime running lights), HVAC,
etc. may affect the download process.
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
Bulletin No.: 20-NA-191
5644477
5431207
Bulletin No.: 20-NA-191
September, 2020
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 Information section of this 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 Engine Control Module. Refer to
K20 Engine Control Module: Programming and
Setup in SI.
5644478
Page 4
September, 2020
Bulletin No.: 20-NA-191
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.
Warranty Information
Important: 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
Use
Published
Engine Control Module
Labor
2810075
Reprogramming with SPS
Operation
Time
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.
Bulletin No.: 20-NA-191
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 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
1
Modified
Released September 17, 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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