GM Bulletin No.: 14628
Date: September 2014

Service Bulletin

SERVICE UPDATE
SUBJECT:

Service Update for Inventory Vehicles Only
Drive Audit for Transmission Noise and Loss of Reverse
Vehicle Limited to 3rd and 4th Forward Gear
Expires October 31, 2015

MODELS:

2015 Chevrolet Corvette
Equipped with 8 Speed Automatic Transmission (M5U)

This service update involves vehicles in dealer inventory only and will expire October 31,
2015.
PURPOSE
This bulletin provides a service procedure to perform a drive audit on all 2015 model year
Corvette vehicles in inventory that are equipped with an 8 speed automatic transmission (M5U).
A small number of transmissions may develop a crack in the triple clutch housing internal to the
transmission, leading to noise, loss of reverse gear, and limiting the driver to 3 rd and 4th forward
gears. The drive audit must be completed before vehicle delivery (and in addition to normal predelivery inspection activities) to identify vehicles with the condition. If the condition is found,
dealers are to replace the transmission under the existing exchange program, see PIP5200A for
details.
This service procedure should be completed on involved vehicles currently in dealership
inventory as soon as possible but no later than October 31, 2015, at which time this
bulletin will expire.
VEHICLES INVOLVED
All involved vehicles are identified by VIN in the Global Warranty Management System –
Investigate Vehicle History Application. Dealership technicians should always check this site to
confirm vehicle involvement prior to beginning any required inspections and/or repairs. It is
important to routinely use this tool to verify eligibility because not all similar vehicles may be
involved regardless of description or option content.
Additionally, a list of involved vehicles currently in dealer inventory is available on the “Service
Update Bulletin Information” link under the “Service” tab in GM GlobalConnect (US) or attached
to the GlobalConnect message (Canada) used to release this bulletin.
Copyright 2012 General Motors. All Rights Reserved.

Page 2

September 2014

Bulletin No.: 14628

PART INFORMATION
No parts are required for the drive audit. If a transmission replacement is necessary, contact
the Product Quality Center as instructed in bulletin PIP5200, Transmission Exchange Program.
SERVICE PROCEDURE
Caution: Ensure the drive audit is performed safely in an area near the dealership. Carefully
listen and observe for the following conditions:


A grinding sound or unusual noise from within the transmission case.



A loss of ‘R’ Reverse gear.



A loss of any of the following forward gears: first, second, fifth, sixth, seventh or eighth
gear.

Tow the vehicle back to the dealership if any of these conditions are present at any time during
the drive audit.
Drive Audit: Part 1
This section can be completed on the dealer parking lot.
1. Start vehicle and press traction control button to turn off traction control
2. Firmly apply the brakes and place the transmission into Reverse.
3. Push the accelerator down to 100% throttle and hold for 2-3 seconds.
4. Release throttle and place transmission in ‘N’ Neutral for 5 seconds.
5. Repeat steps 2 - 4 nine additional times for a total of ten cycles.
Drive Audit: Part 2
The next section requires that the vehicle be taken out on the road or some other open area.
1. Place transmission into manual D2 range.
2. Accelerate vehicle into 2nd gear and accelerate to 3000 RPM and hold for 10 seconds.
3. Brake to a stop.
4. Repeat steps 2 and 3, three additional times
5. Place transmission in ‘D’ Drive and moderately accelerate to approx. 45 mph
6. Brake moderately to a stop.
7. Return car to parking lot.
8. Firmly apply the brakes and place the transmission into ‘R’ Reverse.
9. Push the accelerator down to 100% throttle and hold for 2-3 seconds.
10. Release throttle and place transmission in ‘N’ Neutral for 5 seconds.
11. Repeat steps 9-11, four additional times for a total of five cycles.
12. Place transmission into park.
The audit is now complete.

Page 3

September 2014

Bulletin No.: 14628

If no unusual noise is present, and the transmission is operating normally, no further action is
required.
If unusual noise is present, replace the transmission. Refer to Transmission Replacement in SI
and bulletin PIP5200. Submit a warranty transaction for the drive audit using the labor code
contained in this bulletin. Submit for the transmission replacement under normal warranty.
WARRANTY TRANSACTION INFORMATION
Submit a transaction using the table below.
Labor
Code
9100964

Description
Drive Audit

Labor
Time
0.7

Net
Item
*

* Submit for the actual cost for the gasoline required for the drive audit in Net Item, not to
exceed $4.50 USD, $5.70 CAD.
DEALER PROGRAM RESPONSIBILITY
Dealers must take the steps necessary to ensure that the service update correction has been
made to all involved vehicles in dealer inventory before selling, dealer-trading, or using the
vehicle for demonstration purposes, but no later than October 31, 2015.

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 tools,
equipment, 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 dealer for information on whether your vehicle may benefit from the information.

We Support
Voluntary Technician
Certification