# Service bulletin 21\-NA\-135 A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned. - Type: Service bulletin - NHTSA id: 10245559 - Published by NHTSA: 2023\-11\-29 - Manufacturer's number: 21\-NA\-135 - Manufacturer's date: 2023\-11\-16 - NHTSA component: ENGINE AND ENGINE COOLING; EQUIPMENT; EXTERIOR LIGHTING; ELECTRICAL SYSTEM ## NHTSA's summary This service bulletin provides information to inform dealership personnel about Law Enforcement and Government vehicles that request to disable or enable content. ## The document - [NHTSA's copy of the document (PDF)](https://static.nhtsa.gov/odi/tsbs/2023/MC-10245559-0001.pdf) - [If that address does not open, try this one](https://static.nhtsa.gov/odi/tsbs/2023/MC-10245559-9999.pdf) The document is the manufacturer's. This site does not hold it. ## Components Electrical system, Engine, Equipment and accessories, Lighting ## Vehicles listed - 2019 BUICK CASCADA - 2019 to 2024 BUICK ENCLAVE - 2019 to 2022 BUICK ENCORE - 2023 to 2024 BUICK ENCORE - 2020 to 2024 BUICK ENCORE GX - 2019 to 2024 BUICK ENVISION - 2024 BUICK ENVISTA - 2019 BUICK LACROSSE - 2020 BUICK LACROSSE - 2019 to 2020 BUICK REGAL - 2020 BUICK REGAL TOURX - 2019 CADILLAC ATS - 2020 to 2024 CADILLAC CT4 - 2020 to 2024 CADILLAC CT5 - 2019 to 2020 CADILLAC CT6 - 2021 CADILLAC CT6 - 2019 CADILLAC CTS - 2019 to 2024 CADILLAC ESCALADE - 2019 to 2023 CADILLAC ESCALADE ESV - 2021 CADILLAC ESCALADE NA - 2023 to 2024 CADILLAC LYRIQ - 2019 to 2024 CADILLAC XT4 - 2019 to 2024 CADILLAC XT5 - 2020 to 2024 CADILLAC XT6 - 2019 CADILLAC XTS - 2020 CADILLAC XTS - 2024 CADILLAC redundant LYRIQ - 2019 CHEVROLET 6500 - 2019 to 2024 CHEVROLET BLAZER - 2024 CHEVROLET BLAZER EV - 2022 to 2023 CHEVROLET BOLT EUV - 2019 to 2023 CHEVROLET BOLT EV - 2024 CHEVROLET BOLT EV - 2019 to 2024 CHEVROLET CAMARO - 2019 to 2024 CHEVROLET COLORADO - 2019 to 2024 CHEVROLET CORVETTE - 2019 CHEVROLET CRUZE - 2019 to 2024 CHEVROLET EQUINOX - 2024 CHEVROLET EQUINOX EV - 2019 to 2021 CHEVROLET EXPRESS - 2023 CHEVROLET EXPRESS 2500 - 2023 CHEVROLET EXPRESS 3500 - 2019 to 2023 CHEVROLET EXPRESS CUTAWAY VAN - 2019 to 2020 CHEVROLET IMPALA - 2019 to 2024 CHEVROLET MALIBU - 2019 CHEVROLET MALIBU HYBRID - 2019 to 2021 CHEVROLET SILVERADO 1500 - 2024 CHEVROLET SILVERADO 1500 - 2019 to 2024 CHEVROLET SILVERADO 2500 - 2019 to 2024 CHEVROLET SILVERADO 3500 - 2019 to 2023 CHEVROLET SILVERADO 4500 - 2019 to 2021 CHEVROLET SILVERADO 5500 - 2023 CHEVROLET SILVERADO 5500 - 2019 CHEVROLET SILVERADO 6500 - 2021 to 2023 CHEVROLET SILVERADO 6500 - 2024 CHEVROLET SILVERADO EV - 2019 to 2020 CHEVROLET SONIC - 2019 to 2022 CHEVROLET SPARK - 2019 to 2024 CHEVROLET SUBURBAN - 2021 to 2023 CHEVROLET SUBURBAN 1500 - 2019 to 2024 CHEVROLET TAHOE - 2019 to 2020 CHEVROLET TRAILBLAZER - 2021 to 2024 CHEVROLET TRAILBLAZER - 2019 to 2024 CHEVROLET TRAVERSE - 2019 to 2024 CHEVROLET TRAX - 2019 CHEVROLET VOLT - 2019 CHEVROLET duplicate SILVERADO 5500 - 2024 GMC 3500HD - 2019 to 2024 GMC ACADIA - 2019 to 2024 GMC CANYON - 2022 to 2024 GMC HUMMER EV PICKUP - 2024 GMC HUMMER EV SUV - 2019 to 2024 GMC SAVANA - 2023 GMC SAVANA 2500 - 2023 GMC SAVANA 3500 - 2019 to 2021 GMC SIERRA 1500 - 2024 GMC SIERRA 1500 - 2019 to 2024 GMC SIERRA 2500 - 2019 to 2024 GMC SIERRA 3500 - 2019 to 2020 GMC SIERRA DENALI - 2019 to 2024 GMC TERRAIN - 2022 GMC TERRAIN NA - 2019 to 2023 GMC YUKON - 2019 GMC YUKON DENALI - 2019 to 2024 GMC YUKON XL - 2023 GMC YUKON XL 1500 ## Recalls for the same vehicles and component - [25V876000](/recalls/nhtsa/25V876000.md), 2025-12-17: EQUIPMENT ADAPTIVE/MOBILITY:WHEELCHAIR RESTRAINTS/SECUREMENT:LATCH/ANCHOR: - [2025225](/recalls/tc/2025225.md), 2025-04-24: Engine - [25V274000](/recalls/nhtsa/25V274000.md), 2025-04-24: ENGINE AND ENGINE COOLING:ENGINE:HARD PARTS INTERNAL/MECHANICAL - [24V755000](/recalls/nhtsa/24V755000.md), 2024-10-10: EXTERIOR LIGHTING:LIGHTING CONTROL MODULE - [2024519](/recalls/tc/2024519.md), 2024-09-12: Lights And Instruments - [2024518](/recalls/tc/2024518.md), 2024-09-12: Lights And Instruments - [24V673000](/recalls/nhtsa/24V673000.md), 2024-09-12: EXTERIOR LIGHTING:HEADLIGHTS - [24V575000](/recalls/nhtsa/24V575000.md), 2024-08-01: EQUIPMENT:OTHER:OWNERS/SERVICE/OTHER MANUAL - [24V320000](/recalls/nhtsa/24V320000.md), 2024-05-09: ELECTRICAL SYSTEM:PROPULSION SYSTEM; ELECTRICAL SYSTEM:WIRING - [24V133000](/recalls/nhtsa/24V133000.md), 2024-02-22: ELECTRICAL SYSTEM:ADAS:DRIVER MONITORING:CAMERA/SENSOR; FORWARD COLLISION AVOIDANCE: AUTOMATIC EMERGENCY BRAKING ## Other bulletins for the same vehicles and component - [N262570770\-03](/bulletins/11038560.md), 2026-10-16, Service campaign: ENGINE. Certain vehicles may have a condition in which the thermal break tabs induce stress into the radiator causing a coolant leak. Dealers are to cut the thermal break tabs on the radiator. - [N262576260](/bulletins/11038468.md), 2026-10-15, Service campaign: ENGINE. General Motors has decided to conduct a Voluntary Emission Recall. Certain vehicles may have a condition that could cause a small exhaust leak at the catalytic converter inlet. Dealers are to replace the catalytic converter inlet clamp and to inspect the catalytic converter – replacing it if damage is observed. The repairs will be made at no charge to the customer. - [N262570770\-02](/bulletins/11037486.md), 2026-09-25, Service campaign: ENGINE. Certain vehicles may have a condition in which the thermal break tabs induce stress into the radiator causing a coolant leak. Dealers are to cut the thermal break tabs on the radiator. - [N262570770\-01](/bulletins/11037367.md), 2026-09-18, Service campaign: ENGINE. Certain vehicles may have a condition in which the thermal break tabs induce stress into the radiator causing a coolant leak. Dealers are to cut the thermal break tabs on the radiator. - [N262570770](/bulletins/11037318.md), 2026-09-15, Service campaign: ENGINE. Certain vehicles may have a condition in which the thermal break tabs induce stress into the radiator causing a coolant leak. Dealers are to cut the thermal break tabs on the radiator. - [N242484750\-02](/bulletins/11036594.md), 2026-09-01, Warranty extension: ENGINE. Special Coverage. Certain 2022 model year Buick Encore GX and Chevrolet Trailblazer vehicles, equipped with a 1.2L engine, may have a condition that could cause the turbocharger to fail. If this condition occurs, the Malfunction Indicator Lamp \(Check Engine Light\) will illuminate, and a diagnostic trouble code will set. Additionally, a message may be displayed indicating the vehicle’s available engine power is reduced. This special coverage covers the condition described above for a period of 15 years or 150,000 miles \(240,000 km\), whichever occurs first, from the date the vehicle was originally placed in service, regardless of ownership. For vehicles covered by Vehicle Service Contracts, all eligible claims with repair orders on or after January 14, 2025, are covered by this special coverage and must be submitted using the labor operation codes provided with this bulletin. Claims with repair orders prior to January 14, 2025, must be submitted to the Service Contract provider. Vehicle owners or lessees who paid for repairs referenced in this Special Coverage \(“Customers”\) are eligible for reimbursement of their reasonable and customary expenses in accordance with the procedures specified below. The conditional right to reimbursement is provided by GM solely in the interest of customer satisfaction and is personal to Customers. Customers may not assign and GM does not consent to any assignment of any Customer’s right to submit reimbursement claims, or to receive reimbursement, or any other rights granted by this Special Coverage to any third party, including but not limited to service contract providers, and this Special Coverage is not intended to and does not confer any third party beneficiary, subrogation or contribution rights, or any other rights to reimbursement, against GM, whether in law, equity or otherwise, on any third parties. Dealers are to replace the turbocharger as necessary. The repairs will be made at no charge to the customer. - [N252541251](/bulletins/11035022.md), 2026-07-15, Service campaign: EXTERIOR LIGHTING. Certain vehicles listed above may have a condition in which drivers may not be notified of a rear turn\-signal lamp failure. GM will update software calibrations in the vehicle’s exterior lighting control module. For vehicles that are capable of receiving software changes using wireless over\-the\-air \(OTA\) technology, owners who have accepted applicable terms and conditions will have the opportunity to accept these software changes via OTA without having to bring their vehicle to a dealership. Alternatively, all owners may have the updates performed at a GM dealer. - [N262546590\-01](/bulletins/11035019.md), 2026-07-15, Service campaign: ENGINE. Certain vehicles listed above, may have a condition where coolant leaks from the radiator hose quick connect at the radiator inlet. This special coverage covers the condition described above for a period of 5 years or 60,000 miles \(100,000 km\), whichever occurs first, from the date the vehicle was originally placed in service, regardless of ownership. For vehicles covered by Vehicle Service Contracts, all eligible claims with repair orders on or after July 14, 2026, are covered by this special coverage and must be submitted using the labor operation codes provided with this bulletin. Claims with repair orders prior to July 14, 2026, must be submitted to the Service Contract provider. Vehicle owners or lessees who paid for repairs referenced in this Special Coverage \(“Customers”\) are eligible for reimbursement of their reasonable and customary expenses in accordance with the procedures specified below. The conditional right to reimbursement is provided by GM solely in the interest of customer satisfaction and is personal to Customers. Customers may not assign and GM does not consent to any assignment of any Customer’s right to submit reimbursement claims, or to receive reimbursement, or any other rights granted by this Special Coverage to any third party, including but not limited to service contract providers, and this Special Coverage is not intended to and does not confer any third party beneficiary, subrogation or contribution rights, or any other rights to reimbursement, against GM, whether in law, equity or otherwise, on any third parties. Dealers are to remove the inlet hose and replace the seal. The repairs will be made at no charge to the customer. - [N242468490\-02](/bulletins/11032963.md), 2026-05-28, Service campaign: ELECTRICAL SYSTEM. Certain vehicles may have missing cavity plugs from the rear chassis harness electrical connector. Dealers are to inspect the rear chassis harness and replace missing harness plugs as necessary. - [N262552620](/bulletins/11032588.md), 2026-05-11, Service campaign: ENGINE. Certain vehicles may have a condition that could cause the cylinder 2 glow plug to fail. If this failure occurs, the Malfunction Indicator Light \(Check Engine Light\) will illuminate and a diagnostic trouble code will set. This special coverage covers the condition described above for a period of 15 years or 150,000 miles \(240,000 km\), whichever occurs first, from the date the vehicle was originally placed in service, regardless of ownership. For vehicles covered by Vehicle Service Contracts, all eligible claims with repair orders on or after May 11, 2026, are covered by this special coverage and must be submitted using the labor operation codes provided with this bulletin. Claims with repair orders prior to May 11, 2026, must be submitted to the Service Contract provider. Vehicle owners or lessees who paid for repairs referenced in this Special Coverage \(“Customers”\) are eligible for reimbursement of their reasonable and customary expenses in accordance with the procedures specified below. The conditional right to reimbursement is provided by GM solely in the interest of customer satisfaction and is personal to Customers. Customers may not assign and GM does not consent to any assignment of any Customer’s right to submit reimbursement claims, or to receive reimbursement, or any other rights granted by this Special Coverage to any third party, including but not limited to service contract providers, and this Special Coverage is not intended to and does not confer any third party beneficiary, subrogation or contribution rights, or any other rights to reimbursement, against GM, whether in law, equity or otherwise, on any third parties. Dealers are to replace the cylinder 2 glow plug as necessary. The repairs will be made at no charge to the customer. 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