20NA123

Bulletin No.:
Service Bulletin
Date:
20-NA-123
November, 2020
TECHNICAL
Subject:
Brand:
Malfunction Indicator Lamp (MIL) Illuminated, DTCs U1961, U1983 Set
Model:
Breakpoint:
to
2020
2020
Escalade
Models
2021
2021
Corvette
2020
2020
2021
2021
CT4
Cadillac
Model Year:
from
CT5
Chevrolet
Suburban
GMC
Yukon
Models
Tahoe
from
to
—
—
Engine:
Transmission:
—
—
Involved Region or Country
North America, Middle East, GM Korea Company, Israel, Palestine
Condition
Some customers may comment that the Malfunction Indicator Lamp (MIL) is illuminated.
Technicians may find the following DTCs set:
• U1961 - Control Module Security Hardware Internal Malfunction
• U1983 - Serial Data Gateway Module Security Hardware Internal Malfunction
Cause
This condition may be caused by not clearing the DTCs and also allowing a sleep cycle
after programming or serial data authentication configuration.
Correction
Clear the DTCs and allow the vehicle to go into sleep mode.
Warranty Information
For vehicles repaired under the Bumper-to-Bumper coverage (Canada Base Warranty coverage), use the following
labor operation. Reference the Applicable Warranties section of Investigate Vehicle History (IVH) for coverage
information.
Labor
Operation
Description
Labor Time
2887028*
Scan For DTCs and
Clear Scan
0.3 hr
*This is a unique Labor Operation for bulletin use only.
Version
2
Modified
Released June 02, 2020
November 13, 2020 – Added the Cadillac Escalade Models, Chevrolet Suburban, Tahoe
and GMC Yukon Models and Warranty Information.
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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