GM bulletin PIT3665M
What it saysThis 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. NHTSA’s full summary ↓
GM filed this with NHTSA as a service bulletin dated May 19, 2023, received Jun 13, 2023, about the electrical system. It names 38 model years across Chevrolet and GMC (2016–2024). A service bulletin is not a safety recall: it is the manufacturer telling its dealers how to diagnose or repair a condition, and whether the work is paid for depends on the warranty in force. Quoting the number at a service desk can save a diagnosis.
One page for every brand it was filed under. Each brand’s bulletins: Chevrolet · GMC.
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What the bulletin says
Source: NHTSA's summary of the manufacturer's communicationThis 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.
Document filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| PIT3665M | Service bulletin | May 19, 2023 | 10237671 | not found |
The summary is NHTSA’s abstract of the document, as filed under 49 CFR 579.5. One communication is usually filed as several documents — the bulletin, a dealer notice, an owner letter — and the number on any of them finds this page. A PDF link is shown only once NHTSA’s own server has been seen to serve that document; the rest are checked over the following nights. Quote the number at a service desk; it is what the dealer’s system is keyed on.
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Model years it names
Source: as the manufacturer filed themChevrolet 21 model years
GMC 17 model years
A vehicle page’s bulletin list shows the newest few communications filed against that model year; the count there is every one.
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What owners reported
Source: NHTSA complaint databaseOwners of the 38 model years this bulletin names have filed 8,563 complaints with NHTSA since 2015. 1,303 of them name Electrical System — the same broad component group this bulletin is filed under. NHTSA groups complaints coarsely, so that means the same area of the vehicle, not necessarily the same fault.
On the 2019 Chevrolet Silverado, the 72 owners who gave an odometer reading for Electrical System reported it at a median of 11,750 miles. That figure is one model year’s, not the whole range this bulletin covers — medians from different model years are not averaged.
My doors lock with the car with the keys in the car, my kids were in my car and I got locked out with my keys in it, there was a battery replacement done when I took my car in for a recall notice a month ago (maybe 2 months), also the lock button works but when I push the middle button it will not auto start , when I push the button on…
2018 Chevrolet Suburban · Electrical System · filed with NHTSA May 11, 2021 · ODI 11416217
The contact rented a 2019 Chevrolet Express van. The contact rented the vehicle from budget car rental (1919 5th ave, seattle, wa 98101). While the vehicle was parked on a hill, the contact's mother was exiting from the rear passenger sliding door and without warning, the sliding door closed on the contact's mother's right forearm and…
2019 Chevrolet Express · Electrical System · filed with NHTSA Jun 20, 2019 · ODI 11221488
The contact owns a 2024 GMC Sierra 3500. The contact stated while driving at approximately 60 MPH and towing a Forest River Riverstone Legacy 5th Wheel trailer, the brake pedal was depressed to slow for oncoming stopped traffic; however, the vehicle failed to respond as needed with the “Service Trailer Brake” warning light illuminated.
2024 GMC Sierra 3500HD · Electrical System · filed with NHTSA Jul 9, 2025 · ODI 11672342
In depth: 2024 Chevrolet Silverado electrical problems → · 2023 Chevrolet Silverado electrical problems → · 2021 Chevrolet Silverado electrical problems → · 2019 Chevrolet Silverado electrical problems →
A complaint is one owner’s account, not a defect finding, and a bulletin is not a recall. Nothing here says this bulletin was issued because of these complaints, or that the repair it describes fixed them. Complaint files on this site begin in 2015.
More bulletins about the electrical system
Source: same model, same component group314 other manufacturer communications filed against these GM models under the same component group (electrical system), newest first. The eight newest are listed; the rest are on the Chevrolet list.
| Number | Kind | Dated | NHTSA’s summary |
|---|---|---|---|
| N262565450 | Service campaign | Oct 26, 2026 | Customer Satisfaction Program. Certain vehicles listed above may have a condition in which remanufactured high voltage battery packs were b… |
| N252529080 | Service campaign | Apr 1, 2026 | Service Update. Certain vehicles listed above may be missing a high voltage header plug on the RESS battery pack drive motor connector. Dea… |
| N252515590 | Service campaign | Jan 27, 2026 | Certain vehicles listed above, may have a condition in which the body-to-chassis ground strap may be corroded. Dealers will replace the grou… |
| 24-NA-166 | Service bulletin | Nov 7, 2025 | This technical bulletin provides repair information to correct a customer concern of DTC C1171 C1172 C1173 C1174 Tire Pressure Monitor Senso… |
| 24-NA-227 | Service bulletin | Nov 4, 2025 | This technical bulletin provides repair information to correct a customer concern of Vibration Rattle or Boom at 1800 to 2000 RPM. |
| 25-NA-061 | Service bulletin | Oct 3, 2025 | This technical bulletin provides a procedure to correct the condition of Driver or Passenger Rear Door Handle Will Not Fold In. |
| 18-NA-180 | Service bulletin | Sep 4, 2025 | This Warranty Administration service bulletin provides Lithium-Ion battery Exchange Process and Transaction Submission information. |
| 25-NA-021 | Service bulletin | Jun 7, 2025 | This technical bulletin provides repair information to correct a customer concern of Radio Software Update W23E-178.1.2-M174-SQBR6-93.3. |
Quote the number at the service desk. It is what the dealer’s system is keyed on.
Every manufacturer communication NHTSA holds for Chevrolet and GMC, by the number printed on the letter.
Common questions
Source: NHTSA, 49 CFR 579.5Is GM PIT3665M a recall?
No. A service bulletin is a manufacturer communication filed with NHTSA under 49 CFR 579.5; a safety recall carries an NHTSA campaign number (two digits, a letter, six digits) and a federal duty to repair for free. Check the vehicle’s recalls by VIN at nhtsa.gov/recalls, or on its page here.
Is the PIT3665M repair free?
Not automatically. A service bulletin describes how to diagnose or repair a condition; who pays depends on the warranty in force, any extension, and the dealer. Quoting the number can save a diagnosis either way. Every GM warranty extension on file lists the ones GM has filed.
Which vehicles does PIT3665M cover?
The manufacturer filed it against 38 model years across 2 brands (Chevrolet and GMC): 2022 Chevrolet Equinox, 2023 Chevrolet Express, 2021 Chevrolet Express, 2020 Chevrolet Express, 2019 Chevrolet Express, 2018 Chevrolet Express and more. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.