23-NA-197

Bulletin No.: 23-NA-197
Service Bulletin
Date: April, 2024
TECHNICAL
Subject:
Brand:
Chevrolet
Noise from Transmission Area, Malfunction Indicator Lamp (MIL)
Illuminated
Model:
Corvette
Involved Region or Country
Model Year:
VIN:
from
to
from
to
2020
2023
—
—
Engine:
Transmission:
—
M1L, M1M
North America, Europe, Middle East, Israel, Japan, Thailand, Australia/New Zealand
Some customers may comment on one or more of the following conditions:
• Noise from transmission area
• MIL illuminated
Technicians may find multiple DTCs set in the Transmission Control Module:
• P0746
• P0747
• P0776
• P0777
• P0796
• P0797
• P08C4
• P08C5
• P0867
• P0868
Condition
• P0869
• P1950
• P1955
• P1956
• P1957
• P1958
• P1959
• P1960
• P1961
• P1962
• P1963
• P1966
• P27BA
• P27B9
• P27C2
• P27CA
Copyright 2024 General Motors. All Rights Reserved.
Page 2
April, 2024
• P27C1
• P27C9
• P27D1
• P27D2
• P2714
• P2715
• P2723
• P2724
• P2808
• P2809
• P2817
• P2818
• P282A
• P2829
• P2853
• P2854
• P2855
• P2856
Bulletin No.: 23-NA-197
Bulletin No.: 23-NA-197
April, 2024
Page 3
Cause
6444881
This condition may be caused by a dislodged snap ring in the direct clutch assembly.
- One or more pressure DTCs may set due to the valves sticking in the Main Control
Valve (MCV) Body, due to debris.
- The direct clutch can contact the fluid tubes, stator shaft and/or the transmission housing.
Correction
Refer to the Service Procedure 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.
Service Procedure
Vehicle comes into dealer with MIL illuminated
(pressure DTCs only).
1. Verify that the vehicle has the latest TCM calibrations/update.
2. Perform transmission service diagnostic test.
• If MIL does not return and DTCs do not reset,
return the vehicle to the customer.
• If DTCs return, go to step 3.
3. Refer to Control Valve Body Replacement.
Page 4
April, 2024
Bulletin No.: 23-NA-197
6444679
4. Utilizing a feeler gauge (3), inspect the clearance
between the direct clutch (2) and fluid tube (1).
⇒
If clearance is 0.5 mm, follow service information to replace the MCV, filter and canister
filter.
⇒
If clearance is 0 mm, remove transmission and
go to step 5.
Note: If the direct clutch is seized onto the stator
housing, the transmission will need replacement.
5. Remove the direct clutch. Refer to Direct Clutch
Replacement.
− If the direct clutch has seized to the stator and it
cannot be removed, the transmission will have
to be replaced.
− If the direct clutch cannot be turned easily by
hand, this is evidence that the snap ring has
failed. Remove the direct clutch and inspect the
transmission case. If it is found to have damage
from direct clutch contact, start a technical
assistance case and attach photos.
6444902
Important: Light damage to the housing caused by the
direct clutch contact, will not require replacement. The
graphic above depicts areas of concern.
− If the direct clutch can be removed easily but
has contacted the pipe and stator, replace said
parts as needed. Refer to SI.
Note: The direct clutch and stator housing will need
replacement as the causal part.
6. Install the transmission. Refer to Transmission
Replacement.
7. Perform transmission service fast learn.
− If DTCs reset, return the vehicle to the
customer.
Vehicle comes into dealer with noise from bell
housing area that follows engine RPM and may
also have the MIL illuminated.
1. Verify that the vehicle has the latest TCM calibrations/update.
2. Follow Service Bulletin # 21-NA-049, create TAC
case and attach the PICO file.
3. Contact TAC agent for further direction.
Bulletin No.: 23-NA-197
April, 2024
Page 5
Parts Information
Note: Only select the parts that coincide with the repair
performed. Replace the part with the P/N outlined in
the Electronic Parts Catalog (EPC) in accordance with
the vehicle VIN.
Causal Part
X
Description
SHAFT, STAT
X
CLUTCH, DIR
N/A
BOLT, CLU DIFF HSG CVR
N/A
BOLT, CLU HSG
Part Number
24059055
(M1L)
24059054
(M1M)
24059057
(M1L)
24059053
(M1M)
Qty
1
1
24045094
14
24045732
(M1L)
2
24048636
(M1M)
16
N/A
GASKET, CLU DIFF HSG CVR
24048637
(M1M)
1
N/A
PLUG, MAIN SHF
24299366
1
N/A
RETAINER, INTER CLU SPR
24048649
1
N/A
SPRING, DIR CLU
24299364
1
N/A
BOLT, STAT SHF
24048653
4
11546938
(50 Thread Count - M1L)
N/A
RETAINER, RR WHL DRV SHF UJT
N/A
WASHER, FRT WHL DRV SHF
11611965
2
N/A
NUT, FRT WHL DRV HALF SHF SHLD
11612295
2
N/A
BOLT, RR CRADLE BR
11547752
4
N/A
GASKET, CTLTC CONV
10354707
1
N/A
GASKET, CTLTC CONV
23194206
1
N/A
PIPE, A.TRNS FLUID PUMP DRN
24045747
1
N/A
SEAL, A/TRNS FLUID PUMP PIPE
24299307
4
N/A
FILTER, A/TRNS FLUID
24045729
1
11601876
(58 Thread Count - M1M)
6
N/A
GEAR, A/TRNS FLUID PMP DRV
24299370
1
N/A
BOLT, A/TRNS FLUID PMP DRV GR
24048652
1
N/A
GASKET, A/TRNS FLUID PAN
24047054
1
N/A
SEAL, TRANS FLUID CLR
24299317
2
N/A
FILTER, A/TRNS FLUID
24047742
1
N/A
GASKET, C/VLV BODY
24299343
1
N/A
BODY, C/VLV
24059078
1
N/A
FLUID, A/TRANS
19418016
As Required
N/A
BOLT, A.TRNS FLUID PAN
24045737
As Required
N/A
BOLT, A.TRNS FLUID PAN
24299316
2
Page 6
April, 2024
Bulletin No.: 23-NA-197
Causal Part
Description
Part Number
Qty
N/A
SEAL, TRANS OIL DRN PLUG
24299299
1
N/A
GASKET, A/TRNS FLUID PAN
24048642
1
Note: All pans are specific to DIE of transmission. Technicians should verify all parts are specific to the transmission being
worked on by referring to Service Bulletin #23-NA-156 for identification of transmission.
N/A
Important: Replace the pan only if vehicle has stamped DIE 1 pan. Do Not reuse
DIE 1 pans.
24046450
1
PAN, A/TRNS FLUID (DIE 2)
N/A
GASKET, A/TRNS FLUID PAN (DIE 2)
24047054
1
N/A
GASKET, A/TRNS FLUID PAN (DIE 3)
24048642
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
8486368*
Control Valve Removal and
Contact Inspection
0.8 hr
Add
Stator Shaft and Direct
Clutch Replacement
21.2 hrs
Add
Transmission Replacement
19.0 hrs
*This is a unique Labor Operation for bulletin use only.
Version
1
Modified
Released April 18, 2024
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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