NHTSA ID Number: 10172811
Manufacturer Communication Number: 20NA038
TSB/Document Date: 2020-03-30
Summary
This informational bulletin explains the difference in AFM and DFM engines and what is and is not activated during this occurrence.
Bulletin No.:
Service Bulletin
Date:
20-NA-038
March, 2020
INFORMATION
Subject:
Information on Active Fuel Management (AFM) and Dynamic Fuel Management (DFM)
Usage
This bulletin replaces PIP5663. Please discard PIP5663.
Brand:
Model:
VIN:
from
from
to
CTS
2016
2019
6.2 (LT4)
CT6
2016
2020
6.2 (LTA)
Escalade
2015
2020
5.3 (L83)
6.2 (L86)
3500/4500
Medium
Duty (LCF)
2020
2020
6.6 (L8T)
Camaro
2016
2020
6.2 (LT1, LT4)
2014
2019
6.2 (LT1,
LT4, LT5)
Corvette
Model Year:
to
2020
2020
6.2 (LT2)
Express
2018
2020
4.3 (LV1)
Silverado
2014
2018
4.3 (LV1, LV3)
5.3 (L83)
6.2 (L86)
Silverado
1500 (New
Model)
2019
2019
4.3 (LV3)
5.3 (L82, L84)
6.2 (L87)
Silverado LD
2019
2019
5.3 (L83)
Silverado
1500
2020
2020
4.3 (LV3)
5.3 (L82, L84)
6.2 (L87)
Silverado
2500/3500
2020
2020
6.6 (L8T)
Suburban
2015
2020
5.3 (L83)
6.2 (L86)
Tahoe
2015
2020
5.3 (L83)
6.2 (L86)
Savana
2018
2020
4.3 (LV1)
Sierra
2014
2018
4.3 (LV1, LV3)
5.3 (L83)
6.2 (L86)
Sierra 1500
(New Model)
2019
2019
4.3 (LV3)
Copyright 2020 General Motors
LLC. All Rights Reserved.
Page 2
Brand:
March, 2020
Model:
Model Year:
from
Bulletin No.: 20-NA-038
VIN:
to
from
Engine:
to
5.3 (L82, L84)
6.2 (L87)
Sierra
Limited
2019
2019
4.3 (LV3)
5.3 (L83)
6.2 (L86)
Sierra 1500
2020
2020
4.3 (LV3)
5.3 (L82, L84)
6.2 (L87)
Sierra
2500/3500
2020
2020
6.6 (L8T)
Yukon
Models
2015
2020
5.3 (L83)
6.2 (L86)
Involved Region or Country
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
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
DFM (Dynamic Fuel Management)
Information
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.
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.
Bulletin No.: 20-NA-038
March, 2020
Page 3
AFM/DFM Usage Chart
Vehicles
AFM
VLOM
4 Cylinder
Deactivation
DFM.
OCV's
FDFM
CTS LT4
Yes
Yes
No
No
CT6 LTA
No
Yes
No
No
Camaro LT1
Yes
Yes
No
No
Automatic only. AFM
not active with Manual
trans
Camaro LT4
Yes
No
No
No
Has the hardware, Not
active
Corvette LT1
Yes
Yes
No
No
Auto Trans active,
Manual Trans active in
ECO only
Corvette LT2
No
Yes
No
No
Corvette LT4
Yes
Yes
No
No
Corvette LT5
No
No
No
No
Escalade L83, L86
Yes
Yes
No
No
Express/Savana LV1
No
No
No
No
Silverado/Sierra L83, L86
Yes
Yes
No
No
Suburban/Tahoe/Yukon
L83, L86
Yes
Yes
No
No
Silverado/Sierra L82
No
Yes
Yes
No
Silverado/Sierra L84
No
No
Yes
Yes
Silverado/Sierra L87
No
No
Yes
Yes
Silverado/Sierra HD L8T
No
No
No
No
Silverado/Sierra LV1
No
No
No
No
Silverado/Sierra LV3
Yes
Yes
No
No
3500/4500 Medium
Duty (LCF)
No
No
No
No
None
Notes
Always active
Auto Trans active,
Manual Trans active in
ECO only
Yes
No hardware on LT5
No hardware on LV1
No hardware on L8T
No hardware on L8T
Parts Information
No parts are required for this repair.
Version
1
Modified
Released February 26, 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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TSB/Document ID: 20NA038
Replacement Service Bulletin Number:
MFR Communication Date: 2020-02-26
MFR Internal Campaign ID/Software Version:
Communication Type: Service Bulletin/Repair Instructions
NHTSA Components: FUEL SYSTEM, DIESEL
MFR Component System:
MFR Component Subsystem:
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