21-NA-049

Bulletin No.:
Service Bulletin
Date:
21-NA-049
February, 2024
INFORMATION
Subject:
Diagnostic Aid – PicoScope Information and Setup for Transmission Related Concerns
Brand:
Model:
Chevrolet
Corvette
Model Year:
VIN:
from
to
from
to
2020
2024
—
—
Engine:
Transmission:
All
All
Involved Region or Country
North America, Europe, Middle East, Japan, Australia/New Zealand
Information
This document provides information related to the CH-51450 PicoScope NV tool, set up,
recording, and sound file submission to the GM Technical Assistance Center (TAC) for
noise type concerns within the transmission.
Information
Service Procedure
Note: Ensure you are using a PicoScope purchased
through the GM dealer tool network. PicoScopes
purchased outside of the GM dealer tool network have
different software, which will corrupt the file.
Note: For additional training and information on
PicoScope, visit the Center of Learning and search for
course PicoScope Noise, Vibration, and Harshness
Diagnostics Overview and Oscilloscope Diagnostic Kit
Description and Operation within SI.
If you need to download or update the PicoScope,
follow the steps below:
1. Log into GM GlobalConnect.
2. Click on the "Departments" drop down menu and
select "Service.”
3. Under "Applications" on the service page, select
"Special Tools and Software updates.”
4. You will now be re-directed to
www.gmtoolsandequipment.com (do not access
this site directly as it requires the use of
GlobalConnect to allow downloads).
5. Click the link under "Software Downloads" for the
latest PicoScope software version and a new page
will open.
6. Click the setup links and follow instructions to
update the tool.
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.
Copyright 2024 General Motors LLC. All Rights Reserved.
5751814
1. Place the PicoScope sensor on the bolt head
shown in the image above. This is located on the
right side of the transmission, near the
transmission cooler. This bolt is used to secure a
bracket for the wire harness. The sensor cable can
be run into the passenger compartment with the
engine compartment closed.
Page 2
February, 2024
Bulletin No.: 21-NA-049
Note: Ensure to keep the cable routed away from the
exhaust.
5751818
5751815
2. Open the most current version of GM NVH.
5751816
3. After completing the wizard, go back into the setup
tab under Vibration Signal and select Single
Channel. Select TA148 Interface in the “Box”
dropdown and TA144 Microphone for the “Sensor”
Drop down. Select the Location as Engine
Compartment. Set the Diff Ratio to 3.55. Failure to
change location to engine compartment will
result in you being asked to correct that setting
and resend the data.
Note: If using 3 axis, use center channel only and set
up as single axis.
4. Drive the vehicle to verify condition and record a
Pico data file of the concern.
⇒ If diagnosing an acceleration or deceleration
related concern, please hold the acceleration
steady for 3-5 seconds After book marking
while recording or allow a 3-5 second
deceleration while recording. Tipping in and out
of the throttle shows that it is load related but
does not help isolate the source.
⇒ If diagnosing a steady speed condition, please
try and hold the steady speed for at least 5
seconds during the recording as it also allows
for better isolation on our end when reviewing
the files.
Bulletin No.: 21-NA-049
February, 2024
Page 3
6. The next box allows you to save the vehicle
information as well as customer information and
notes in the Notes box. This could be sensor
location, sensor direction and even road surface
name, etc. Click Ok when you are done adding
information.
7. If PICO scope data shows readings under 85
decibels, vehicle noise is deemed as a normal
characteristic.
8. Create an e-mail to [email protected] in
the U.S. and [email protected]
in Canada and in the subject line Put Vibration,
your BAC, and last 8 of the VIN.
Note: For Middle East, Japan, or other countries,
contact your local TAC for submission instructions.
Parts Information
No parts are required for this repair.
5751819
5. While the reviewed file is on the screen, click File
Save. It should be formatted as .pddata
5751820
Version
5
Modified
Released March 04, 2021
Revised July 29, 2022 – Added the 2022 and 2023 Model Years, Transmission RPO
M1M, Europe to the Involved Region or Country section and step 7.
Revised June 06, 2023 – Changed Transmission RPO to All, added Australia/New
Zealand to Involved Region or Country section and added an Important statement under
Information section.
Revised November 17, 2023 – Added the 2024 Model Year.
Revised January 31, 2024 – Added Information to the Service Procedure under Step 3
and Step 4.
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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