21-NA-199

Bulletin No.:
Service Bulletin
Date:
21-NA-199
August, 2022
INFORMATION
Subject:
Information on Installation of a New Thermal Bypass Valve (TBV)
Attention: The new TBV will be stamped with the number 70 and should only be replaced once
during any transmission repair, including Customer Concern Not Duplicated (CCND).
Brand:
Chevrolet
GMC
Model:
Model Year:
from
to
VIN:
from
to
Engine:
Express
2021
2021
March 18, 2021
All
Silverado
2016
2018
EOP
All
Silverado LD
2019
2019
EOP
All
Fort Wayne:
March
16, 2021,
5.3 (L82)
Fort Wayne:
April 26, 2021
4.3 (LV3)
Silao: April
06, 2021
All
Silverado 1500
(New Model)
2019
2021
Silverado
2500HD/3500HD
2020
2021
March 20, 2021
All
Suburban
2016
2020
EOP
All
Tahoe
2016
2020
EOP
All
SOP
Savana
2021
2021
March 18, 2021
All
Sierra
2016
2018
EOP
All
Sierra Limited
2019
2019
EOP
All
Fort Wayne:
March
16, 2021,
5.3 (L82)
Fort Wayne:
April 26, 2021
4.3 (LV3)
Silao: April
06, 2021
All
Sierra 1500
(New Model)
2019
2021
Sierra
2500HD/3500HD
2020
2021
March 20, 2021
All
Yukon Models
2016
2020
EOP
All
Copyright 2022 General Motors LLC. All Rights Reserved.
Transmission:
MYC, MYD
Page 2
August, 2022
Bulletin No.: 21-NA-199
Involved Region or Country
North America, Canada
Condition
Some customers may comment on one or more of the following conditions:
• MIL illuminated
• Harsh Shifts
• Slip
• Surge
• Shudder
• Harsh Garage Shifts
• Harsh Range Shifts
• Noise
• Whine
• Growl
• Shake
• Vibration
• Delayed Shifts
Note: Review of the Global Warranty Management (GWM) system. This will indicate if
the TBV has been replaced.
Correct the existing customer condition following published Service Information.
Correction
5897301
Note: The TBV should be replaced one time for any transmission repair including
Customer Concern Not Duplicated (CCND). Once the TBV Part Number 86774933,
stamped with “70” as shown above is installed, it does not need to be replaced again
unless it is determined the TBV has failed.
⇒ The Transmission Cooler Bypass Valve (TBV) should be replaced with a new
(TBV) that has cooler operating temperature and should be replaced when
any transmission repair is performed including Customer Concern Not
Duplicated (CCND).
Note: The “70” may be difficult to read as a dot print maybe stamped over the “70”.
– The new TBV only needs to be replaced once. The new valve has a 70 stamped into
the bottom of the valve. The “70” stamp is visible on the valve when installed on the
transmission.
– The revised TBV has a full open temperature of 158f (70c). The previous TBV had a
full open temperature of 194f (90c).
Bulletin No.: 21-NA-199
August, 2022
Page 3
Parts Information
Causal Part
N/A
Description
Part Number
Vehicle
Qty
86774933
2016-2018 Silverado/
Sierra, 2019 Silverado
LD/Sierra Limited (steel
lines), Suburban,
Tahoe, Yukon
1
85547828
Silverado Sierra
2500HD/3500HD
1
85563685
2019-2021 Silverado/
Sierra (aluminum
lines), Express/Savana
1
Seal
23135703
All
1
SEAL, TRANS FLUID
CLR PIPE FTG
(O-RING)
12650609 (aluminum
lines)
All
2
23277649 (steel lines)
DEXRON VI
Transmission Fluid
88865601 (US)
19421425 (Canada)
All
1
Transmission Cooler
Bypass Valve (TBV)
N/A
N/A
N/A
Warranty Information
Note: This repair is an addition to any other
transmission repair. A second line item should be
added to the Repair Order.
For vehicles repaired under the Powertrain coverage,
use the following labor operation. Many repairs will not
require additional labor for the TBV replacement as it
may be necessary to remove the TBV to complete the
transmission repair. Reference the Applicable
Warranties section of the Investigate Vehicle History
(IVH) for coverage information.
Labor Operation
Description
Labor Time
8486048*
Install Transmission Thermal Bypass Valve (TBV) During Any
Repair That Involves Requires Removal of the Transmission
0.2 hr
Add
Install Transmission Thermal Bypass Valve (TBV) For Any
Repair Including CCND That Does Not Require Removal of the
Transmission
0.6 hr
*This is a unique Labor Operation for Bulletin use only.
Version
5
Modified
Released September 24, 2021
Revised October 05, 2021 - Removed Escalade Models, 2014 from Suburban, Tahoe and
Yukon models and 2020 Silverado 1500 and Sierra 1500 from Model section.
Revised October 19,2021 - Removed 2014 and 2015 Silverado and Sierra and 2015
Suburban, Tahoe and Yukon from Model section.
Revised December 10, 2021 - Added Express, Savana, Silverado 1500 (New Model),
and Sierra 1500 (New Model) to Model Section and Update Parts Information section.
Revised July 26, 2022 - Added Suburban, Tahoe, Yukon to Parts Information 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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