Bulletin No.:

Service Bulletin

Date:

18-NA-378
September, 2019

TECHNICAL
Subject:

Surge, Chuggle, Fishbite, Shudder Feel During Driving Maneuvers

Brand:

Model:

Cadillac

XT4

Model Year:

VIN:

from

to

2019

2019

from

to

Engine:

Transmission:

2.0L (LSY)

9T50
Automatic
(M3H)

Involved Region or Country

North America, Middle East, Israel

Condition

Some customers may comment on one or more of the following conditions:
• Surge
• Chuggle
• Fishbite
• Shudder

Cause

This condition may be caused by fluid contamination from the stack plate heat exchanger.
Important: It may be necessary to drive a minimum of 321 km (200 mi) if slight shudder
remains after the repair.
Perform a transmission fluid level and condition check. Refer to Transmission Fluid Level
and Condition Check in SI.
1. Refer to the latest version of Bulletin 08-07-30-035 to obtain a glycol test kit.
2. Perform a glycol test.
• If no glycol contamination is found (no color change), drain and refill the
transmission using DEXRON VI. Refer to Transmission Fluid Drain and Fill in SI
and no further work is needed.
• If the glycol level is 50 ppm or above:
1.
Perform a transmission disassemble. Refer to Engine Coolant/Water in
Transmission in SI.
2.
Replace the transmission fluid cooling exchanger. Refer to Automatic
Transmission Fluid Cooling Exchanger Replacement in SI.

Correction

Parts Information
Note: Only select the ancillary parts that coincide with
the repair performed.
Causal Part

Description

Part Number

Qty

X

EXCHANGER, A/TRNS FLUID CLG

24290617

1

N/A

RING, FRT WHL DRV INTER SHF RET

90121202

2

N/A

WASHER, FRT WHL DRV SHF

11611965

2

N/A

NUT, FRT WHL DRV SHF (M27 X 2
X 6H)

11612295

2

N/A

BOLT, FRT STAB SHF INSL CLA

11547610

4

N/A

SEAL, TRANS FLUID CLR PIPE
(SLIMLINE WASHER 3/8")

25874797

2

Copyright 2019 General Motors LLC. All Rights Reserved.

Page 2

September, 2019

Bulletin No.: 18-NA-378

Causal Part

Description

Part Number

Qty

N/A

BOLT, TRANS MT TRANS SI (M12 X
1.75 X 61)

11547918

4

N/A

BOLT, TRANS RR MT BRKT

11611642

2

N/A

BOLT, HFH, M10X1.5X75 (TRANS
FRT MT)

11588747

2

N/A

BOLT, HFH, M10X1.5X55, 25.7 THD,
22.3 OD, 10.9 STL, GMW3359 (TRANS
FRT MT)

11588743

2

N/A

SEAL, PROP SHF TO DIFF CARR
INTERFACE

23321677

1

N/A

RETAINER, PROP SHF TO DIFF CARR
INTERFACE

23432713

1

N/A

SEAL, PWR TRFER U PROP SHF

23206807

1

N/A

RETAINER, PWR TRFER U PROP SHF

23206808

1

N/A

GASKET, EXH SYS INTER

22816982

2

N/A

SEAL, OIL LVL IND TUBE

12670252

1

N/A

FLUID, A/TRANS (DEXRON VI) (1 QT/
0.946 LITRES)

Refer to EPC

Refer to EPC

Warranty Information
Note: Only select the Labor Operation that coincides
with the repair performed.
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

8480858*

Glycol Test

0.3 hr

Add

Automatic Transmission
Fluid Pan Drain and Fill

0.4 hr

8480868*

Automatic Transmission
Overhaul w/ Fluid Cooling
Exchanger Replacement

Use Actual
Clock Time

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

Version

5

Modified

Released December 17, 2018
January 22, 2019 – Added the AWD Torque Converter part number to the Parts
Information section.
February 04, 2019 – Added Warranty Information.
May 16, 2019 – Updated the Correction section and Warranty Information and added the
WPC Part Request Form.
August 27, 2019 – Updated the Correction, Parts Information and Warranty Information to
remove transmission replacement information and add Cooling Exchanger information.
The WPC Part Request Form was also removed.

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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