NHTSA ID Number: 10205547
Manufacturer Communication Number: 21NA076
Summary
This technical bulletin provides a procedure to repair a worn spring in the transmission to correct the customers concern.
2 Affected Products
Vehicles
Condition
Some customers may comment that their vehicle has developed a harsh 5-4 downshift and a harsh 1-2 upshift.
– The condition developed after approximately 25,000 miles (40,000 km). The harsh shift conditions may only be present when the transmission temperature is above approximately 110 F (43 C) degrees.
– The transmission may have acceptable transmission shift quality at lower operating temperatures.
Cause
This condition may be caused by the 2-3-4-6-8 Return Spring (527), has degraded overtime contributing to the condition
Correction
Replace the 2-3-4-6-8 Piston (526) and the 2-3-4-6-8 Return Spring and reseal the 2-3-4- 6-8 and 4-5-6-7-8 Reverse Clutch Assemble following published Service Information procedures.
Service Procedure
Refer to 2-3-4-6-8 and 4-5-6-7-8 Reverse Clutch Assembly Removal and 2-3-4-6-8 and 4-5-6-7-8 Reverse Clutch Disassemble and Assemble in SI.
Parts Information
| Causal Part | Description | Part Number | Qty |
| X | Piston, 2-3-4-6-8 Clutch | 24268881 | 1 |
| X | Spring, 2-3-4-6-8 Clutch Piston Return | 24292256 | 1 |
| N/A | Seal 2-3-4-6-8 Clutch Piston Dam INNER | 24250187 | 1 |
| N/A | Seal, Trans Fluid Cooler Pipe Fitting | 23135703
GM 23135703 SEAL-TRANS FLUID CLR PIPE FTG
Last update on 2026-06-09 / Affiliate links / Images from Amazon Product Advertising API | 1 |
| N/A | Bolt, HFH Eng Motor Bracket | 11588740
GM Genuine Parts 11588740 Multi-Purpose Bolt
Last update on 2026-06-09 / Affiliate links / Images from Amazon Product Advertising API | 3 |
| N/A | Gasket, Exh System Outlet Flange | 22971963 | 2 |
| N/A | Bolt, Transaxle T/C | 11588468
11588468 BOLT 4.115
Last update on 2026-06-09 / Affiliate links / Images from Amazon Product Advertising API | 6 |
| N/A | Ring, 1-3-5-6-7 Clutch Fluid Seal | 24266594
GM Genuine Parts 24266594 Automatic Transmission 1-3-5-6-7 Clutch Fluid Seal
Last update on 2026-06-09 / Affiliate links / Images from Amazon Product Advertising API | 2 |
| N/A | Gasket, A/Trans Front Support Cover | 24284849 | 1 |
| N/A | Seal, A/Trans Case Front Cover | 24251906 | 1 |
| N/A | Seal, A/Trans Case Front Cover | 24281790 | 1 |
| N/A | Ring, 4-5-6-7-8 Rev Clutch Piston | 24270446 | 1 |
| N/A | Seal, 4-5-6-7-8 Rev Piston Outer | 24261006 | 1 |
| N/A | Seal, 4-5-6-7-8 Rev Piston Inner | 24250211 | 1 |
| N/A | Ring, 2-3-4-6-8 Clutch Piston Dam Retainer | 24261071 | 1 |
| N/A | Seal, 2-3-4-6-8 Clutch Piston Dam OUTER | 24250195 | 1 |
| N/A | Seal, 2-3-4-6-8 Clutch Piston | 24250198 | 1 |
| N/A | Seal, 4-5-6-7-8 Rev Clutch Piston | 24259271 | 1 |
| N/A | Seal, 4-5-6-7-8 Rev Clutch Piston Stop | 24250207 | 1 |
| N/A | Seal, 2-3-4-6-8 Clutch Piston Dam | 24261024 | 2 |
| N/A | Seal, Turbine Shaft O-ring kit | 08662686 | 1 |
| N/A | Bolt, A/Trans Case Front Cover | 11548201 | 11 |
| N/A | Mobil 1 Synthetic ULV HP Fluid (US) | 19417577 | As Required |
| N/A | Mobil 1 Synthetic ULV HP Fluid (Can) | 19418066 |
SEOCONTENT-START
Copyright 2021 General Motors
LLC. All Rights Reserved.
Service Bulletin Bulletin No.: 21-NA-076
Date: November, 2021
TECHNICAL
Subject: Harsh 5-4 Downshift and Harsh 1-2 Upshift
This bulletin replaces PIP5747A. Please discard PIP5747A.
Brand: Model:
Model Year: VIN: Engine: Transmission:
from to from to
Chevrolet
Colorado
2017 2017 M5T
GMC Canyon
Involved Region or Country North America
Condition
Some customers may comment that their vehicle has developed a harsh 5-4 downshift
and a harsh 1-2 upshift.
– The condition developed after approximately 25,000 miles (40,000 km). The harsh shift
conditions may only be present when the transmission temperature is above
approximately 110 F (43 C) degrees.
– The transmission may have acceptable transmission shift quality at lower operating
temperatures.
Cause This condition may be caused by the 2-3-4-6-8 Return Spring (527), has degraded
overtime contributing to the condition
Correction
Replace the 2-3-4-6-8 Piston (526) and the 2-3-4-6-8 Return Spring and reseal the 2-3-4-
6-8 and 4-5-6-7-8 Reverse Clutch Assemble following published Service Information
procedures.
Page 2 November, 2021 Bulletin No.: 21-NA-076
Service Procedure
Refer to 2-3-4-6-8 and 4-5-6-7-8 Reverse Clutch
Assembly Removal and 2-3-4-6-8 and 4-5-6-7-8
Reverse Clutch Disassemble and Assemble in SI.
Parts Information
Causal
Part
Description Part
Number
Qty
X Piston, 2-3-4-6-8
Clutch 24268881 1
X
Spring, 2-3-4-6-8
Clutch Piston
Return
24292256 1
N/A
Seal 2-3-4-6-8
Clutch Piston
Dam INNER
24250187 1
N/A
Seal, Trans Fluid
Cooler Pipe
Fitting
23135703 1
N/A Bolt, HFH Eng
Motor Bracket 11588740 3
N/A
Gasket, Exh
System Outlet
Flange
22971963 2
N/A Bolt, Transaxle
T/C 11588468 6
N/A Ring, 1-3-5-6-7
Clutch Fluid Seal 24266594 2
N/A
Gasket, A/Trans
Front Support
Cover
24284849 1
N/A Seal, A/Trans
Case Front Cover 24251906 1
N/A Seal, A/Trans
Case Front Cover 24281790 1
N/A Ring, 4-5-6-7-8
Rev Clutch Piston 24270446 1
Causal
Part
Description Part
Number
Qty
N/A Seal, 4-5-6-7-8
Rev Piston Outer 24261006 1
N/A Seal, 4-5-6-7-8
Rev Piston Inner 24250211 1
N/A
Ring, 2-3-4-6-8
Clutch Piston
Dam Retainer
24261071 1
N/A
Seal, 2-3-4-6-8
Clutch Piston
Dam OUTER
24250195 1
N/A Seal, 2-3-4-6-8
Clutch Piston 24250198 1
N/A Seal, 4-5-6-7-8
Rev Clutch Piston 24259271 1
N/A
Seal, 4-5-6-7-8
Rev Clutch
Piston Stop
24250207 1
N/A
Seal, 2-3-4-6-8
Clutch
Piston Dam
24261024 2
N/A Seal, Turbine
Shaft O-ring kit 08662686 1
N/A Bolt, A/Trans
Case Front Cover 11548201 11
N/A
Mobil 1 Synthetic
ULV HP
Fluiid (US)
19417577
As Required
N/A
Mobil 1 Synthetic
ULV HP
Fluiid (Can)
19418066
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
8481988* 2-3-4-6-8 Piston and Return Spring Replacement 11.9 hr
Add W/4WD 2.8 hr
*This is a unique Labor Operation for Bulletin use only.
Version 3
Modified Released June 15, 2021
Revised October 27, 2021 – Increased Part 24261024 to QTYof 2 and Added Part
Number 24250187 to Parts Information section.
Revised November 05, 2021 – Update Parts Information section.
SEOCONTENT-END
1 Associated Document
Manufacturer Communications
NHTSA ID Number: 10201291
Manufacturer Communication Number: PIP5747A
Summary
This Preliminary information communicates to the dealer technician that engineering is investigating root cause of a harsh 1-2 and/or 5-4 shift on the 2017 Chevrolet
Colorado and the 2017 GMC Canyon after mileage accumulation of approximately 25,000 miles. This Pi has been updated to refer the dealer technician to bulletin 21-NA-076 for information on how to address this concern.
1 Associated Document
Manufacturer Communications
Bulletin No.: PIP5747A
Published date: 06/21/2021
- Mobil 1 Synthetic LV ATF HP is a high performance synthetic automatic transmission fluid that delivers extended transmission life with improved thermal stability
- Has outstanding long-term frictional properties to help improve and extend transmission efficiency, smooth shifting performance, and fuel economy
- Exceptional thermal and oxidation stability keep transmissions clean to help provide outstanding performance even under severe driving conditions
- Helps provide reliable lubrication at temperatures down to -78F (-61C), and supports viscosity retention under the most severe high-temperature operating conditions
- Recommended for use in modern high-performance vehicles requiring Dexron HP ATF
- Outstanding long-term frictional properties. Helps to improve and extend transmission efficiency, smooth shifting performance and fuel economy.
- Exceptional thermal and oxidation stability. Keeps transmissions clean to help provide outstanding performance even under severe driving conditions.
- Outstanding film-strength and anti-wear properties. Significant wear reduction which can contribute to long transmission life.
- Excellent low-temperature fluidity. Helps to provide prompt and reliable lubrication at ambient temperatures down to -61º C.
- Exceptional shear stability. Viscosity retention even under some of the severest heavy duty, high temperature operating conditions.
- Mobil 1 Synthetic LV ATF HP 1 Quart
- For use in 95% of vehicles including most CVTs in operation with US registered light duty applications
- High performance conditioning agents prolong seal elasticity to prevent leaks
- Improved durability & transmission life with anti-wear technology to avoid costly repairs
- Enhanced high & low temp performance supports transmission fluid in all weather situations
- Full synthetic formula with advanced additives protects against transmission breakdown better than conventional fluids
- Formulated with full-synthetic base stocks and advanced additive technology to meet the challenging demands of automatic transmissions
- Enhanced anti-shudder protection for smooth shifting and maximum power transfer
- Developed with anti-wear technology to help improve transmission durability
- Engineered with a proprietary blend of base oils and advanced additives to provide better oil flow at low temperatures and greater film protection at higher temperatures
Last update on 2026-05-27 / Affiliate links / Images from Amazon Product Advertising API
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