GM bulletin 23-NA-134
What it saysThis service bulletin provides repair information to correct a customer concern of a SES light or Service Transmission Soon message appearing in the DIC. NHTSA’s full summary ↓
GM filed this with NHTSA as a service bulletin dated Aug 9, 2023, received Sep 12, 2023, about the equipment. It names 6 model years across Buick and Cadillac (2017–2019). 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: Buick · Cadillac.
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What the bulletin says
Source: NHTSA's summary of the manufacturer's communicationThis service bulletin provides repair information to correct a customer concern of a SES light or Service Transmission Soon message appearing in the DIC.
Trouble codes it names: P26C8 U135A all 2 read from the document itself; NHTSA’s summary names none
Document filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| 23-NA-134 | Service bulletin | Aug 9, 2023 | 10242200 | PDF, 132 KB |
What the document itself lists
The manufacturer titles it “U135A Set After Replacement of Trans Range Control Module”.
Labour operation and the time the manufacturer allows
| Operation | Description | Time |
|---|---|---|
| 2889708 | Program Transmission Range Control Module for Compatibility Issue | 0.3 hrs |
Read by machine from the document NHTSA serves (7 pages), read Sep 30, 2026. A part number is shown only where it matches GM’s own catalogue shape, an operation only with its code and time, and a description only where the reader got it whole; anything it could not settle is left out, and the PDF is the record. Times are the manufacturer’s warranty allowances, not a quote. Listings and prices on eBay Motors are the seller’s.
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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.
Model years it names
Source: as the manufacturer filed themBuick 3 model years
Cadillac 3 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 6 model years this bulletin names have filed 280 complaints with NHTSA since 2015. 102 of them name Electrical System, Power Train — 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 2017 Cadillac XT5, the 16 owners who gave an odometer reading for Power Train reported it at a median of 19,000 miles. That figure is one model year’s, not the whole range this bulletin covers — medians from different model years are not averaged.
The contact owns a 2017 Buick Lacrosse. The contact stated that after his wife had parked and turning off the vehicle, moments later the vehicle was restarted and the check engine and TCM warning lights remained illuminated. Additionally, the transmission shifter failed to shift out of park. The vehicle towed to the local dealer.
2017 Buick LaCrosse · Power Train · filed with NHTSA Dec 29, 2023 · ODI 11562549
2nd time this issue occurred. 1st time was in 2019 and it took two weeks for the dealership to figure out it was the battery. While driving the car, the electronics go crazy, the engine stops for a split second, brakes are lost for a split second, cruise control turns off, every possible alarm displays on the dash.
2018 Cadillac XT5 · Electrical System · filed with NHTSA Jun 13, 2020 · ODI 11328651
Service stability track light came on. Brought to Mechanic hooked up to computer. No code shown. Mechanic says car is fine. Keep it off for 15 minutes and the computer will reset. Driving on the highway Emergency brake came on by itself and stopped the vehicle all caution lights lit up on on the dashboard.
2019 Cadillac XT5 · Electrical System · filed with NHTSA Jan 14, 2023 · ODI 11501784
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 equipment
Source: same model, same component group49 other manufacturer communications filed against these GM models under the same component group (equipment), newest first. The eight newest are listed; the rest are on the Buick list.
| Number | Kind | Dated | NHTSA’s summary |
|---|---|---|---|
| PIP5601B | Service bulletin | Jul 18, 2025 | This Preliminary Information communication provides information to the technician about vibration complaints that are one of the most challe… |
| 17-NA-073 | Service bulletin | Mar 5, 2025 | This warranty administration bulletin provides policy information with the field action courtesy transportation policy. |
| 17-NA-331 | Service bulletin | Jan 17, 2025 | Rear View Camera Guidelines Not Present at Times Condition Some customers may report that the Rear View Camera (RVC) guidelines are temp… |
| 22-NA-038 | Service bulletin | Dec 14, 2024 | This warranty bulletin provides information on Customer Concern Not Duplicated (CCND) Labor Operation Numbers. |
| 18-NA-263 | Service bulletin | Dec 14, 2024 | This warranty administration bulletin provides policy information for variable diagnostic time allowances on select labor operations… |
| 24-NA-040 | Service bulletin | Oct 11, 2024 | This service bulletin provides information on All hazmat parts being returned to the Warranty Parts Center (WPC) must be shipped using Centr… |
| 23-NA-154 | Service bulletin | Oct 2, 2024 | This bulletin provides information on Warranty Administration â Required Operating Procedures - 8 Points (U.S. Only). |
| 23-NA-219 | Service bulletin | Sep 21, 2024 | This service bulletin provides information on Concerns or Questions Regarding Installation of Dealer Installed Accessories. |
Quote the number at the service desk. It is what the dealer’s system is keyed on.
Every manufacturer communication NHTSA holds for Buick and Cadillac, by the number printed on the letter.
Common questions
Source: NHTSA, 49 CFR 579.5Is GM 23-NA-134 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 23-NA-134 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 23-NA-134 cover?
The manufacturer filed it against 6 model years across 2 brands (Buick and Cadillac): 2019 Buick LaCrosse, 2018 Buick LaCrosse, 2017 Buick LaCrosse, 2019 Cadillac XT5, 2018 Cadillac XT5, 2017 Cadillac XT5. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.