NHTSA ID Number: 11006377
Manufacturer Communication Number: 20-NA-038
TSB/Document Date: 2024-08-15
Summary
This informational bulletin explains the difference in AFM and DFM engines and what is and is not activated during this occurrence.
Bulletin No.: 20-NA-038
Service Bulletin
Date: July, 2024
INFORMATION
Subject:
Information on Active Fuel Management (AFM) and Dynamic Fuel
Management (DFM) Usage
This bulletin replaces PIP5663. Please discard PIP5663.
Brand:
Model:
VIN:
to
CTS
2016
2019
CT5
2022
2024
6.2L (LT4)
CT6
2019
2020
4.2L (LTA)
2015
2020
5.3L (L83)
6.2L (L86)
2021
2024
6.2L (L87)
2023
2024
6.2L (LT4)
3500/4500 Medium
Duty (LCF)
2020
2024
6.6L (L8T)
Camaro
2016
2024
6.2L (LT1, LT4)
2014
2019
6.2L (LT1, LT4,
LT5)
2020
2024
6.2L (LT2)
Express
2018
2024
4.3L (LV1), 6.6L
(L8T)
Silverado
2014
2018
Silverado 1500 (New
Model)
2019
2019
4.3L (LV3)
5.3L (L82, L84)
6.2L (L87)
Silverado LD
2019
2019
5.3L (L83)
Silverado 1500
2020
2021
4.3L (LV3)
5.3L (L82, L84)
6.2L (L87)
2022
2022
Silverado 1500
2023
2024
Silverado 2500/3500
2020
2024
Escalade Models
Corvette
Silverado 1500 - LTD
(RPO J21, VIN Digit
12 = 4 or less)
Silverado 1500 - New
(RPO J22, VIN Digit
12 = 5 or greater)
Copyright 2024 General Motors
. All Rights Reserved.
from
Engine:
from
Model Year:
to
6.2L (LT4)
—
—
4.3L (LV1, LV3)
5.3L (L83)
6.2L (L86)
5.3L (L82, L84)
6.2L (L87)
6.6L (L8T)
—
Page 2
Brand:
July, 2024
Model:
Model Year:
Bulletin No.: 20-NA-038
VIN:
from
to
Suburban
2015
2024
5.3L (L83, L84)
6.2L (L86, L87)
Tahoe
2015
2024
5.3L (L83, L84)
6.2L (L86, L87)
Savana
2018
2022
4.3L (LV1), 6.6L
(L8T)
Sierra
2014
2018
4.3L (LV1, LV3)
5.3L (L83)
6.2L (L86)
Sierra 1500 (New
Model)
2019
2019
4.3L (LV3)
5.3L (L82, L84)
6.2L (L87)
Sierra Limited
2019
2019
4.3L (LV3)
5.3L (L83)
6.2L (L86)
Sierra 1500
2020
2021
4.3L (LV3)
5.3L (L82, L84)
6.2L (L87)
2022
2022
Sierra 1500
2023
2024
Sierra 2500/3500
2020
2024
6.6L (L8T)
Yukon Models
2015
2024
5.3L (L83, L84)
6.2L (L86, L87)
Sierra 1500 - Limited
(RPO J21, VIN Digit
12 = 4 or less)
Sierra 1500 - New
(RPO J22, VIN Digit
12 = 5 or greater)
Involved Region or Country
from
Engine:
to
5.3L (L82, L84)
6.2L (L87)
North America, Europe, Uzbekistan, Russia, Middle East, Iraq, Israel, Palestine, Argentina, Brazil, Bolivia, Chile, Colombia, Ecuador, Paraguay, Peru, Uruguay, Venezuela,
Japan, Cadillac Korea (South Korea), GM Korea Company, China, Taiwan, Thailand, Singapore, Philippines, Egypt, Other Africa, South Africa, Australia, New Zealand.
AFM (Active Fuel Management)
To provide maximum fuel economy under light load driving conditions, the engine control
module (ECM) will command the cylinder deactivation system ON to deactivate engine
cylinders 1, 7, 6, and 4, switching to a V4 mode. The engine will operate on 8 cylinders, or
V8 mode, during engine starting, engine idling, and medium to heavy throttle applications.
AFM – active fuel management strategy which deactivates the lifters on specific cylinders. On V8 engines, it deactivates half of the cylinders (1,7,6 and 4) and on V6 engines,
it deactivates only 2 of the cylinders (3 and 6). For LTA and LT2 engines, the deactivation
occurs on cylinders 2, 3, 5 and 8.
LOMA – lifter oil manifold assembly is only used on legacy AFM applications.
Information
DFM (Dynamic Fuel Management)
Dynamic Fuel Management (DFM) is recognized as active fuel management technology
with the additional ability to deactivate any combination of cylinder valves for an internal
combustion engine. This technology combines millisecond-accurate torque control with
cylinder deactivation to optimize fuel consumption of spark ignited engines. The control of
every cylinder event optimizes engine operation such that peak efficiency is obtained
throughout the range of engine operation. DFM extends cylinder deactivation to all cylinders, which allows for a large variety of firing sequences. DFM can have rotating cylinder
deactivation patterns as well as fixed patterns. For rotating patterns, which cylinders are
being deactivated can change with each subsequent engine cycle. Transitions between
firing sequences is done in a continuous fashion, making the transitions seamless and
transparent to the vehicle operator.
Bulletin No.: 20-NA-038
July, 2024
Page 3
DFM – dynamic fuel management which can deactivate the lifter on any cylinder at any
time. Unlike AFM, this can result any many different types of firing patterns, some of
which are fixed patterns (like ¼, ½, ¾) and others which are rotating (like 1/5, 1/3, 2/5,
2/3). This is only available on small block engines (L84 and L87).
OCV – oil-controlled valve is only used on small block engines. These provide faster
response times than LOMA and are required for DFM (on L84 and L87). OCVs are also
used on L82 for AFM.
Refer to the AFM/DFM Usage Chart below.
Important: Service agents must comply with all
International, Federal, State, Provincial, and/or
Local laws applicable to the activities it performs
under this bulletin, including but not limited to
handling, deploying, preparing, classifying,
packaging, marking, labeling, and shipping
dangerous goods. In the event of a conflict
between the procedures set forth in this bulletin
and the laws that apply to your dealership, you
must follow those applicable laws.
AFM/DFM Usage Chart
Vehicles
AFM VLOM
4 Cylinder
Deactivation
DFM. OCV's
FDFM
None
Notes
CTS LT4
Yes
Yes
No
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TSB/Document ID: 20-NA-038
Replacement Service Bulletin Number:
MFR Communication Date: 2024-07-23
MFR Internal Campaign ID/Software Version:
Communication Type: Service Bulletin/Repair Instructions
NHTSA Components: FUEL/PROPULSION SYSTEM
MFR Component System:
MFR Component Subsystem:
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