NHTSA ID Number: 10219291
Manufacturer Communication Number: 21-NA-275
Summary
This service bulletin provides repair information to correct customer concerns of Rear Wheel Lock Up, ABS Event, Loud Bang and a Flashing “D” on Driver Information Center (DIC) when Lightly or Moderately Accelerating Forcing an 8-7 or 8-6 Downshift.
Condition
Some customers may comment on the following conditions while lightly to moderately accelerating, forcing an 8-7 or 8-6 downshift between 64-96 km/h (40-60 mph) with the transmission at operating temperature:
- Rear wheel/tire lockup or an ABS event
- Loud bang
- Very hard 8-7 or 8-6 downshift
- Feeling of hitting a large pothole or large speed bump
- Flashing “D” on the DIC
Cause
This condition may be caused by an internal control valve body issue.
Correction
Replace the valve body assembly. Refer to Control Valve Body Replacement in SI.
Parts Information
| Description | Part Number | Qty |
| VALVE, CONT (CT4, CT5, CT6) | 24044192 | 1 |
| VALVE, CONT (2020 T1 LD) | 24044189 | 1 |
| VALVE, CONT (Second Design 2020 and 2021 T1 HD) | 24044274 | 1 |
| VALVE, CONT (First Design 2020 T1 HD) | 24047334 | 1 |
| VALVE ASM,- CONT | 1 | |
| VALVE ASM,- CONT | 24043770 | 1 |
| VALVE ASM,- CONT | 24043767 | 1 |
| SEAL, A/TRNS AUX FLUID PUMP | 24047734 | 1 |
| Transmission Fluid – (U.S.A.) | 19352619 | As Required |
| Transmission Fluid – (Canada) | 19352620 |
25 Affected Products
Vehicles
| MAKE | MODEL | YEAR |
| CADILLAC | CT4 | 2020-2021 |
| CADILLAC | CT5 | 2020-2021 |
| CADILLAC | CT6 | 2019-2021 |
| CADILLAC | ESCALADE | 2021 |
| CADILLAC | ESCALADE ESV | 2021 |
| CHEVROLET | SILVERADO 1500 | 2020-2021 |
| CHEVROLET | SILVERADO 2500 | 2020-2021 |
| CHEVROLET | SILVERADO 3500 | 2020-2021 |
| CHEVROLET | SUBURBAN | 2021 |
| CHEVROLET | SUBURBAN 1500 | 2021 |
| CHEVROLET | TAHOE | 2021 |
| GMC | SIERRA 1500 | 2020-2021 |
| GMC | SIERRA 2500 | 2020-2021 |
| GMC | SIERRA 3500 | 2020-2021 |
| GMC | YUKON | 2021 |
1 Associated Document
Manufacturer Communications
Bulletin No.: 21-NA-275
Date: August, 2022
- Exceeds OEM specs Dexron ULV, Mercon ULV, Mercedes Benz 236.17, Nissan Matic P, JATCO 9 Speed, BMW 83-22-2-413-477 ATF 7 and many other ULV application - Silverado, Escalade, Yukon, Tahoe, Suburban, Escalade, BMWs, Ford Mustang, Ford Super Duty F250, F350, F-550, Raptor, Lincon, Ford Explorer, Navigator, GMC Sierra, Chevrolet Camaro SS, BMW / Mini
- EXCEPTIONALLY SMOOTH SHIFTING:: Delivers ultra-smooth shifting, long-term stability, high shear and oxidation stability, and eliminates shudder, slipping, or gear sticking even under severe loads such a towing or hauling - EXTENDED DRAIN: Long drain intervals of up to 100,000 miles+ for standard driving and 70,000 miles for heavy-duty applications
- TRUE ALL SEASON - ALL SERVICE: Engineered for extreme conditions with a pour point down to -50°F, very high thermal stability for hot weather and high film strength for continuous severe service use like towing, hauling in modern trucks.
- GM 10L80/10L90, Escalade (2021+ with 10L80), CT6 3.0TT and 4.2TT (2019+ with 10L80), Silverado 1500 (2019+ with 10L80), Camaro SS / ZL1 (2017+ with 10L80/90), Tahoe and Suburban (2021+ with 10-speed), Sierra 1500 (2019+ with 10L80), and Yukon and Yukon XL with 10 speed transmissions
- Helps enhance transmission cooling function
- Designed to protect metal surfaces from wea
- Formulated to condition gaskets
- Some ACDelco GM Original Equipment parts may have formerly appeared as GM Genuine Parts (OE) or ACDelco Professional
- ACDelco GM Original Equipment parts are designed, engineered and tested to rigorous standards, and are backed by General Motors
.
- Meets and exceeds DEXRON ULV & MERCON ULV Specs -Formulated to meet OEM specifications for modern Ford and GM 10-speed transmissions requiring ultra-low viscosity ATF like DEXRON ULV and MERCON ULV.
- Enhanced with FR3 Friction Reducer - Features our proprietary FR3 for smoother gear shifts, reduced wear, and improved thermal stability—delivering superior transmission performance.
- Professional Grade, DIY Ready - Perfect for shops and advanced DIYers. Compatible with most ATF fluid exchange systems and transmission service kits. Always consult your vehicle's manual for correct specification.
- Maximum Performance - GREEN DIAMOND ULV ATF also provides increased oxidation and thermal stability, deposit and sludge prevention, reduced breakdown, longer drain intervals and higher wear resistance than our competitors.
- Compatible With Ford & GM 10-Speed Vehicles - Designed for use in vehicles requiring ULV ATF including Ford F-150, Expedition, and GM Silverado, Sierra, Tahoe with 10L80, 10R80, or 10-speed automatic transmissions.
- Formulated with premium synthetic base oils to achieve low viscosity and minimize deposits
- Provides excellent thermal and oxidation performance
- Durable friction modifiers help prevent shudder
- Advanced anti-wear technology to better prevent gear wear
SEOCONTENT-START
Copyright 2022 General Motors
LLC. All Rights Reserved. Service Bulletin Bulletin No.: 21-NA-275 Date: August, 2022 TECHNICAL Subject: Rear Wheel Lock Up, ABS Event, Loud Bang and a Flashing “D” on Driver Information Center (DIC) when Lightly or Moderately Accelerating, Forcing an 8-7 or 8-6 Downshift Brand: Model: Model Year: VIN: Engine: Transmission: from to from to (Automatic) Cadillac CT4 2020 2021 — — LSY MQA CT5 MHS CT6 2019 2021 MHS Escalade Models 2021 2021 LM2 MQC Chevrolet Silverado 1500 2020 2021 LM2 MQB Silverado 2500HD/3500HD 2020 2021 L5P MGM, MGU Suburban 2021 2021 LM2 MQC Tahoe 2021 2021 LM2 MQC GMC Sierra 1500 2020 2021 LM2 MQB Sierra 2500HD/3500HD 2020 2021 L5P MGM, MGU Yukon 2021 2021 LM2 MQC Involved Region or Country North America, Uzbekistan, Russia, Middle East, Israel, Palestine, Bolivia, Chile, Colombia, Ecuador, Paraguay, Peru, Uruguay, Venezuela, China, Australia, New Zealand. Condition Some customers may comment on the following conditions while lightly to moderately accelerating, forcing an 8-7 or 8-6 downshift between 64-96 km/h (40-60 mph) with the transmission at operating temperature: • Rear wheel/tire lockup or an ABS event • Loud bang • Very hard 8-7 or 8-6 downshift • Feeling of hitting a large pothole or large speed bump • Flashing “D” on the DIC Cause This condition may be caused by an internal control valve body issue. Correction Replace the valve body assembly. Refer to Control Valve Body Replacement in SI. Page 2 August, 2022 Bulletin No.: 21-NA-275 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. Parts Information Use the VIN and refer to the GM Electronic Parts Catalog (EPC) to determine the proper part to order. Causal Part Description Part Number Qty X VALVE, CONT (CT4, CT5, CT6) 24044192 1 X VALVE, CONT (2020 T1 LD) 24044189 1 X VALVE, CONT (Second Design 2020 and 2021 T1 HD) 24044274 1 X VALVE, CONT (First Design 2020 T1 HD) 24047334 1 X VALVE ASM,- CONT 1 X VALVE ASM,- CONT 24043770 1 X VALVE ASM,- CONT 24043767 1 N/A SEAL, A/TRNS AUX FLUID PUMP 24047734 1 N/A Transmission Fluid 19352619 (U.S.A.) 19352620 (Canada) As Required Warranty Information For vehicles repaired under the Emission coverage, use the following labor operation. Reference the Applicable Warranties section of Investigate Vehicle History (IVH) for coverage information. Labor Operation Description Vehicle Labor Time 8486158* Test Drive/ Diagnostic/ Control Valve Body Replace CT4 2.2 hrs CT5 CT6 2.0 hrs Silverado 1500 3.9 hrs Sierra 1500 Silverado 2500HD/ 3500HD 2.0 hrs Sierra 2500HD/ 3500HD Escalade 3.1 hrs Suburban Tahoe Yukon *This is a unique Labor Operation for bulletin use only. Version 3 Modified Released January 25, 2022 Revised May 19, 2022 – Updated Parts Information section and added Unique Labor Operation number in Warranty Information section and added more Keywords. Revised August 23, 2022 – Added an Important statement and updated Transmission Fluid Quantity in the Parts Information section. Additional SI Keywords: shift, down, brake, braking, unwanted 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. WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION
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