# Service bulletin PIT3665M 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: 10237671 - Published by NHTSA: 2023\-06\-13 - Manufacturer's number: PIT3665M - Manufacturer's date: 2023\-05\-19 - NHTSA component: ELECTRICAL SYSTEM: INTEGRATED TRAILER BRAKE CONTROL ## NHTSA's summary This Preliminary Information communication advises the technician that the Hydro\-Boost is not serviceable and will need to be replaced if the brake pedal moves or applies on its own at a full turn. ## The document - [NHTSA's copy of the document (PDF)](https://static.nhtsa.gov/odi/tsbs/2023/MC-10237671-0001.pdf) - [If that address does not open, try this one](https://static.nhtsa.gov/odi/tsbs/2023/MC-10237671-9999.pdf) The document is the manufacturer's. This site does not hold it. ## Components Electrical system ## Vehicles listed - 2001 to 2004 CADILLAC ESCALADE - 1998 to 2005 CHEVROLET ASTRO - 2002 to 2004 CHEVROLET AVALANCHE 1500 - 2022 CHEVROLET EQUINOX - 1998 to 2021 CHEVROLET EXPRESS - 2023 CHEVROLET EXPRESS 3500 - 1998 CHEVROLET SILVERADO 1500 - 1999 to 2014 CHEVROLET SILVERADO 1500 - 2017 to 2019 CHEVROLET SILVERADO 1500 - 2021 CHEVROLET SILVERADO 1500 - 2023 CHEVROLET SILVERADO 1500 - 2015 to 2016 CHEVROLET SILVERADO 2500 - 2020 CHEVROLET SILVERADO 2500 - 2022 CHEVROLET SILVERADO 2500 - 2024 CHEVROLET SILVERADO EV - 2001 to 2004 CHEVROLET SUBURBAN - 2016 to 2019 CHEVROLET SUBURBAN - 2001 to 2004 CHEVROLET TAHOE - 1998 to 2005 GMC SAFARI - 1998 to 2023 GMC SAVANA - 1998 GMC SIERRA 1500 - 2006 to 2010 GMC SIERRA 1500 - 2012 to 2014 GMC SIERRA 1500 - 2017 to 2019 GMC SIERRA 1500 - 2021 to 2023 GMC SIERRA 1500 - 2000 GMC SIERRA 2500 - 2003 to 2005 GMC SIERRA 2500 - 2015 to 2016 GMC SIERRA 2500 - 2020 GMC SIERRA 2500 - 1999 GMC SIERRA 3500 - 2001 to 2002 GMC SIERRA 3500 - 2011 GMC SIERRA 3500 - 2024 GMC SIERRA 3500 - 2001 to 2004 GMC YUKON - 2003 to 2007 HUMMER H2 ## Recalls for the same vehicles and component - [2024294](/recalls/tc/2024294.md), 2024-05-24: Electrical - [24V320000](/recalls/nhtsa/24V320000.md), 2024-05-09: ELECTRICAL SYSTEM:PROPULSION SYSTEM; ELECTRICAL SYSTEM:WIRING - [2023210](/recalls/tc/2023210.md), 2023-04-06: Electrical - [23V247000](/recalls/nhtsa/23V247000.md), 2023-04-06: ELECTRICAL SYSTEM:WIRING - [2021407](/recalls/tc/2021407.md), 2021-07-01: Electrical - [2021166](/recalls/tc/2021166.md), 2021-03-18: Electrical - [21V189000](/recalls/nhtsa/21V189000.md), 2021-03-18: ELECTRICAL SYSTEM:12V/24V/48V BATTERY:CABLES - [2019631](/recalls/tc/2019631.md), 2019-12-12: Electrical - [19V888000](/recalls/nhtsa/19V888000.md), 2019-12-12: ELECTRICAL SYSTEM:12V/24V/48V BATTERY:CABLES - [19V644000](/recalls/nhtsa/19V644000.md), 2019-09-06: ELECTRICAL SYSTEM: INSTRUMENT CLUSTER/PANEL; SEAT BELTS:FRONT:WARNING LIGHT/DEVICES ## Other bulletins for the same vehicles and component - [N252529080](/bulletins/11030439.md), 2026-04-01, Service campaign: ELECTRICAL SYSTEM. Service Update. Certain vehicles listed above may be missing a high voltage header plug on the RESS battery pack drive motor connector. Dealers are to inspect the RESS pack connectors and install the proper HV Header Plug if missing. - [N252515590](/bulletins/11027795.md), 2026-01-27, Service campaign: ELECTRICAL SYSTEM. Certain vehicles listed above, may have a condition in which the body\-to\-chassis ground strap may be corroded. Dealers will replace the ground strap. - [25\-NA\-119](/bulletins/11024500.md), 2025-10-27, Service bulletin: AIR BAGS; ELECTRICAL SYSTEM. This service bulletin provides information on the Service Safety Restraint Message displayed on the DIC Airbag malfunction indicator illuminated. - [25\-NA\-108](/bulletins/11024499.md), 2025-10-27, Service bulletin: POWER TRAIN; ELECTRICAL SYSTEM. This bulletin provides a procedure to inspect and verify the drive shafts are over extending past the 5mm tolerance, causing the customers concern of a fluid leak under the vehicle. - [25\-NA\-044](/bulletins/11024498.md), 2025-10-27, Service bulletin: ELECTRICAL SYSTEM; FUEL/PROPULSION SYSTEM. This service bulletin provides information for dealers/technicians on SPS2 Hybrid/EV Battery Data Retrieval for Service High Voltage DTCs. - [24\-NA\-202](/bulletins/11024496.md), 2025-10-27, Service bulletin: ELECTRICAL SYSTEM; FUEL/PROPULSION SYSTEM. This service bulletin provides dealers with Warranty Administration information on North American Charging Standard \(NACS\) DC Adapter Warranty Claim Information. - [23\-NA\-202](/bulletins/11024487.md), 2025-10-25, Service bulletin: ELECTRICAL SYSTEM; FUEL/PROPULSION SYSTEM. This service bulletin provides information on High Voltage Drive Motor Battery \- TAC Approval and Exchange Program for BrightDrop, Chevrolet Silverado EV, and GMC Sierra EV, HUMMER EV/SUV. - [23\-NA\-170](/bulletins/11024486.md), 2025-10-25, Service bulletin: ELECTRICAL SYSTEM; ENGINE. This bulletin advises the tech to inspect deeper into what may be to main cause of an engine failure. - [23\-NA\-201](/bulletins/11024378.md), 2025-10-21, Service bulletin: SERVICE BRAKES; ELECTRICAL SYSTEM; STEERING. This service bulletin advises the technician of a possible loose ground that may be causing customer concerns of Loss of Steering Assist and/or Loss of Brake Assist and Malfunction Indicator Lamp \(MIL\) Illuminated. - [18\-NA\-180](/bulletins/11024324.md), 2025-10-16, Service bulletin: ELECTRICAL SYSTEM; FUEL/PROPULSION SYSTEM. This Warranty Administration service bulletin provides Lithium\-Ion battery Exchange Process and Transaction Submission information. 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