16NA361

Bulletin No.:
Service Bulletin
Date:
16-NA-361
October, 2019
INFORMATION
Subject:
Brand:
Information on Transmission Harsh 1-2 Shift Upon First Start Up/Shift of the Day Under
Light Throttle
Model:
2016
2019
CT6
2016
2020
CT4
2020
2020
Escalade
Models
2015
2017
CTS Models
Chevrolet
Camaro
2016
2020
Colorado
(VIN S, T)
2017
2020
Corvette
2015
2019
Express
2017
2020
Silverado
2015
2018
Silverado LD
2019
2019
Silverado
1500 (New
Model)
2019
2020
Canyon
Savana
GMC
VIN:
to
ATS
Cadillac
Model Year:
from
2017
from
Engine:
Transmission:
to
Automatic 8L45
(M5N) 8L90
(M5X, MQE)
Automatic 8L90
(M5U, MQE)
Automatic 8L45
(M5T) 8L90
(M5U,
M5X, MQE)
2020
2020
Sierra
2015
2018
Sierra
Limited
2019
2019
Sierra 1500
(New Model)
2019
2020
Yukon
2015
2017
Automatic 8L45
(M5T) 8L90
(M5U,
M5X, MQE)
Automatic 8L90
(M5U, MQE)
Involved Region or Country
North America and N.A. Export Regions
Condition
Some customers may comment that the transmission exhibits a harsh 1-2 shift on the first
shift of the day, typically under light throttle.
Cause
This condition is due to the initial clutch fill time of the 2-3-4-6-8 (C4) clutch.
Information
Some customers may experience a flare condition on the first 1-2 shift of the day or after
the vehicle has been parked for several hours. The condition may have developed after
the replacement of a complete transmission assembly or the replacement of the stator
support to correct a delayed engagement condition. This is most likely to occur under
light throttle conditions. Subsequent 1-2 shifts have acceptable shift feel. Replacing
transmission components will not correct the condition.
Copyright 2019 General Motors LLC. All Rights Reserved.
Page 2
October, 2019
Bulletin No.: 16-NA-361
Correction
Important: Replacing transmission components or complete assemblies will not improve
the condition.
The first 1-2 shift of the day may be harsh. The customers’ vehicle should be compared to
a like vehicle under the same driving conditions. Do Not replace any parts for this
condition.
Note: This condition will not impact the designed performance or reliability of the vehicle.
Version
6
Modified
Revised Nov. 18, 2016 - Revised the Cause section.
Revised April 6, 2017 - Added models and Revised the Condition, Cause and Correction
sections.
Revised July 20, 2017 - Updated Model section.
Revised May 21, 2018 - Updated Model section.
Revised October 08, 2019 - Added 2020 CT4 and updated models to 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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