Bulletin No.:

Service Bulletin

Date:

21-NA-047
March, 2021

TECHNICAL
Subject:

Shake and/or Shudder During Light Throttle Acceleration Between 25 and 80 MPH (40
and 128 KM/H) at Steady Speed

Note: This procedure should only be completed once
per vehicle. Any vehicle that returns with suspect
shudder should be diagnosed utilizing published
diagnostics, GDS, PICO Scope or other diagnostic
tools. Sometimes shudder is not caused by the torque
converter clutch (TCC). In some instances, shudder is
fish bite, chuggle, surge or vibration.
Brand:

Model:

Chevrolet

Colorado

GMC

Canyon

Involved Region or Country

Model Year:

Breakpoint Date:

from

to

from

to

2019

2020

March
1, 2019

EOP

Engine:

Transmission:
M5T

United States, Canada, Middle East Operations (MEO)
Some customers may comment that their vehicle is experiencing a shake and/or shudder
during light throttle acceleration between 25 and 80 mph (40 and 128 km/h) steady state
driving when transmission is not actively shifting gears.

Condition

⇒ The condition may be described as if they are driving over rumble strips or
rough pavement.
Shudder can be evident in both Drive and M7 mode.
Shudder cannot be evident with TCC locked (zero slip) or TCC released (open)

Cause

Correction

This condition may be due to Torque Converter Clutch (TCC) Shudder.
Note: This procedure should only be completed once per vehicle. Any vehicle that
returns with suspect shudder should be diagnosed utilizing published diagnostics, GDS,
PICO Scope or other diagnostic tools. Sometimes shudder is not caused by the torque
converter clutch (TCC). In some instances, shudder is fish bite, chuggle, surge or
vibration.

⇒ If a customer presents a vehicle with a similar complaint, follow normal SI
diagnostics.

Diagnosis Instructions:
Use one of the following tests methods to assist in
proper diagnosis of TCC shudder. Evaluate vehicle on
a smooth road with transmission sump temperature
between 122°F (50°C) - 158°F (70°C), engine speed
between 1100 - 1500 rpm, and engine torque between
150 - 250 Nm.

Copyright 2021 General Motors LLC. All Rights Reserved.

Perform TCC slip control test and TCC shudder/
picoscope test within this procedure.
Repeat claims should have pan inspected for further
diagnosis. Additional information may be found in
Service Information – Torque Converter Diagnosis.

Page 2

March, 2021

TCC Slip Control Test
TCC SLIP
CONTROL
TEST
RESULT

TCC RPM
Slip Peak
to Peak
(At Steady
Throttle)

ACTION

Note

Normal

Below
20 rpm

Do nothing

-

Degraded

Near 60 rpm
repeating

Flush
transmission
fluid

Shudder,
surge, fish
bite likely

1.
2.
3.
4.

Utilize TIS2Web / GDS2 / MDI service tool.
Select module diagnostics – TCM.
Select TCC data for session log/data collection.
Collect data between 55 to 70 MPH (89-112 km/h)
steady state (steady throttle) with minimum 15
seconds.

5751734

5. Zoom into 15 second window for analysis (1).
6. For line graph evaluation, set parameter minimum
and maximum to values (2) stated for comparison
(Fig 1).

Bulletin No.: 21-NA-047

Bulletin No.: 21-NA-047

March, 2021

Page 3

5752700

7. Evaluate collected data with line graph and
compare data from a normal (1) and degraded. (2).

TCC Shudder/Picoscope Test
TCC
SHUDDER
TEST
RESULT

TCC
Shudder
Frequency
(At Slight
Tip In)

ACTION

Note

Normal

None

Do nothing

-

23 to 27 Hz

Flush
transmission
fluid

Intermittent /
Audible

Shudder

The PicoScope (CH-51450) essential tool and NVH
software or GDS must be used to confirm TCC
Shudder, Engine, Tire, or Driveline component related
conditions.
5751612

The graph above depicts a degraded frequency or
shudder.
Note: Any vehicle that returns with suspect shudder
should be diagnosed utilizing published diagnostics,
GDS, PICO Scope or other diagnostic tools.
Sometimes shudder is used to describe an engine
problem and is not caused by the torque converter
clutch (TCC).
Vehicles that are presented with TCC shudder should
have the appropriate fluid exchange procedure
completed. Diagnosis beyond the customer compliant
is not required if vehicle was built prior to production
dates indicated above.

5751608

The graph above depicts a normal frequency.

Special Tools
DT-52263 Transmission Fluid Exchange Kit:
To confirm TCC Shudder, record the PicoScope data
while driving in stated conditions. Minimize extraneous
vibration input by testing on a smooth road and correct

Page 4

March, 2021

Bulletin No.: 21-NA-047

any other known vehicle vibration issues (tires, brakes,
etc.) before conducting test. If TCC Shudder is present,
a vibration peak will appear. TCC Shudder vibration
frequency is stationary in 8th gear. If the vibration
frequency follows vehicle speed or engine speed, then
it is NOT TCC Shudder.
• DT-52263-1 Block Assembly (includes fluid drain
hose, spring clamp)
• DT-52263-2 Cooler Line Plug (qty 3) (use with rear
differential cooler and Camaro V8 non rear
differential cooler)
• DT-52263-3 ½” Cooler Line Flush Adapter for
2019 Silverado and Sierra
• DT-52263-4 3/8” Hose Adapter (6” long with 2
hose clamps)
• DT-52263-5 Radiator Cooler Drain Adapter

3763203

•

DT-51190 Transmission Oil Fill Adapter

5181938

•

GE-47716-2 Graduated Bucket

1215917

DT-45096 TransFlow Cooler Flush Machine

4733125

DT-45096-31 TransFlow Adapter (one of two pieces
from DT-45096-30)

Bulletin No.: 21-NA-047

March, 2021

Service Procedure
Initial TransFlow Flush Machine Setup
Important: The prepping procedure only needs to be
completed if the DT-45096 supply reservoir has
DEXRON VI fluid in it and has not been converted to
use the new blue label Mobil 1 Synthetic LV ATF HP
fluid.
Note: The prepping procedure only needs to be
completed if HP fluid is not in the supply reservoir.

Page 5

or aftermarket additive packages will result in a low
concentration level of new fluid and will not provide
satisfactory results.
1. Fill the DT-45096 with 20 quarts of HP fluid.
2. Raise the vehicle on a hoist.

1. Connect the TransFlow adapter DT-45096-31 to
the supply line of the DT-45096 TransFlow
machine.

5182541

3. Install the DT-45096-31 TransFlow adapter (1) to
the DT-51190 fluid fill adapter (2).

5180884

2. Switch the DT-45096 TransFlow to Idle.
3. Connect power leads to the vehicle 12-volt DC
supply.
4. Turn the TransFlow main switch ON.
5. Connect air supply to the DT-45096.
6. Place the TransFlow supply hose with adapter
DT-45096-31 into a waste reservoir using care not
to spill the expelled fluid.
7. Switch the DT-45096 TransFlow to Flow and allow
all the fluid in the supply reservoir to be removed
and placed in the waste reservoir.
8. Switch the control switch back to idle.

Fluid Exchange Procedure - Colorado, Canyon,
Silverado, Sierra, Yukon Denali and Escalade
Models with an Accessible Transmission Oil
Cooler Line Block Assembly
Important: This procedure must be followed as
published. The exchange process is required to obtain
proper level of new blue label Mobil 1 Synthetic LV ATF
HP fluid. Intermixing of other types of transmission fluid

5180563

4. Remove the transmission oil cooler pipe assembly
from the transmission.
5. Install the DT-52263-1 Adapter Block Assembly
(1), reusing the seal from the transmission oil
cooler pipe assembly.
6. Tighten the bolt (2) to 22 Y (16 lb ft).

Page 6

March, 2021

7. Place the hose (3) in the GE-47716-2 Graduated
Measuring Bucket, utilizing a Spring Clamp to
retain the hose.

Bulletin No.: 21-NA-047

Caution: DO NOT REMOVE MORE THAN 3 QUARTS
OF FLUID AS IT COULD CAUSE FLUID PUMP
CAVITATION AND POSSIBLY DAMAGE THE
TRANSMISSION.
12. Utilizing the graduated bucket, start the engine and
run 30- 45 seconds until 3 quarts of fluid is
expelled.
13. Shut the engine off immediately.
14. Connect the DT-45096 to the vehicle battery 12
volts and connect shop air to the air connection.

3723844

8. Remove the level set plug (1) from the
transmission.
Important: DO NOT over tighten the DT-51190 as it
can be damaged by excessive torque. DO NOT exceed
9 Y (80 lb in).
9. Install the DT-51190/DT-45096-31 assembly and
hand tighten as shown in the graphic above.

5181027

15. Switch the DT-45096 TransFlow to Flow and add 4
quarts of HP to the transmission.

5181020
3723839

10. Connect the TransFlow fluid feed (supply) line (3)
to the DT-45096-31 adapter (2).
11. Lower the vehicle.

16. Switch the DT-45096 TransFlow to Idle (Reducing
fluid level in the TransFlow from 20–16).

Bulletin No.: 21-NA-047

March, 2021

17. Switch the TransFlow DT-45096 to Flow and start
the engine:
17.1. Add a maximum of 4 quarts of HP Fluid to
the transmission, turn the TransFlow switch
to idle once 4 quarts have been added, while
allowing 4 additional quarts of oil to fill the
DT-graduated bucket (Reducing fluid level in
the TransFlow from 16 – 12).
Note: DO NOT add additional transmission fluid until
the 4 quarts of oil have been removed from the
transmission (Reducing fluid level in the TransFlow
from 12–8).

Page 7

22. Install the level set plug.

Tighten
Tighten the plug to 9 Y (80 lb in).
23. Remove DT-52263-1 Adapter Block Assembly
from the transmission.
24. If equipped, remove the Thermal By-Pass Block
from the cooler pipes on the Escalade, Silverado,
Sierra and Yukon Models.

17.2. Repeat step 17.1.
17.3. Add a maximum of 5 quarts of HP fluid to the
transmission while allowing 5 additional
quarts of oil to fill the DT-graduated bucket
(Reducing fluid level in the TransFlow from
8 – 3).

1762577

25. Install DT-45096-31 adapters (1) to the
transmission oil cooler lines.
26. Connect the DT-45096 TransFlow to the
DT-45096-31 adapters.

5181401

18.
19.
20.
21.

17.4. Shut the engine off once 16 quarts of fluid
have been collected.
17.5. Properly dispose of the expelled
transmission fluid.
Raise the vehicle.
Disconnect the DT-45096 TransFlow feed (supply)
line from DT-45096-31 TransFlow adapter.
Using care, remove DT-45096-31/DT-51190 as an
assembly.
Remove the DT-51190 fluid fill adapter from
DT-45096-31 hose.

5210461

27. Switch the DT-45096 TransFlow to Flush.

Page 8

March, 2021

28. Flush the vehicle cooler and lines using 2 quarts of
HP fluid.
⇒ Flush 1 quart of fluid through the lines, then
switch the hose connections and flush 1 quart
of fluid in the opposite direction.
29. Remove the DT-51190/DT-45096-31 assembly.
30. If equipped, install the Thermal By-Pass Block from
the cooler pipes on the Escalade, Silverado, Sierra
and Yukon Models.
31. Install the transmission oil cooler pipe using a new
cooler block seal.
32. Partially lower the vehicle.
33. Start the engine.
34. Using care, shift the transmission through all
forward ranges and Reverse.
35. Shift the transmission into Park.
36. Perform the Transmission Fluid Level and
Condition Check outlined below in this procedure:
36.1. Get the transmission fluid temperature to the
proper temperature.
36.2. Install the level set plug.

Tighten
Tighten the plug to 9 Y (80 lb in).
The TCC shudder condition should be directional
improved immediately after the fluid exchange
procedure. It may take up to 320 km (200 mi) for the
TCC shudder condition to be eliminated. It is not a
requirement for the dealer to drive the vehicle 320 km
(200 mi). The customer should be advised that the full
effect will take up to 320 km (200 mi) and a minimum of
two cold to operating temperature drive cycles.

Bulletin No.: 21-NA-047

Causal
Part

X

Description

Mobil 1 Synthetic
LV ATF HP
(Available only
through Local GM
Oil Distributors)

Part
Number

Qty

19417577
(US - 1
quart)
19418066
(Canada 0.946L/1 qt)

20

N/A

N/A

SEAL, TRANS
FLUID CLR PIPE

20

Drum 55
gallon
19417904
(US)

1

23135703

1

Warranty Information
For vehicles repaired under the Powertrain coverage,
use the following labor operation. Reference the
Applicable Warranties section of Investigate Vehicle
History (IVH) for coverage information.
Labor
Operation

Description

Labor Time

8481958*

Diagnostic Test and Fluid
Exchange

1.8 hrs

Add

DT-45096 Prep (Not
required unless the fluid is
not Mobil 1 Synthetic LV
ATF HP)

0.1 hr

*This is a unique Labor Operation for Bulletin use only.

Parts Information
Note: Only select the parts that coincide with the repair
performed.
Version

1

Modified

Released March 04, 2021

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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