This is the kind of two-fer every automaker dreads: two federal investigations for two problems that have nagged General Motors vehicles for at least a year, announced a day apart. On Aug. 20, the National Highway Traffic Safety Administration said it would investigate complaints of 6.2-liter V8 engine failures in full-size pickups and SUVs even after those vehicles had been repaired in a previous recall.
But then a day later, NHTSA’s Office of Defects Investigation announced a second GM inquiry, this one potentially impacting nearly 1.2 million vehicles. There hasn’t been a recall yet associated with the problem, which is tagged as “Electronic Brake Module Component Failure.” The investigation impacts 12 nameplates across all four GM brands, and two from joint-venture partner Honda: the Honda Prologue and Acura ZDX, which were both produced in GM’s Spring Hill, Tennessee, plant.
2026 Buick Enclave rear 3/4 angle in silver while parkedJared Rosenholtz/CarBuzz/Valnet
Spindle Fractures In eBoost System?
The ODI’s investigation began in April 2024 when the safety agency received complaints that drivers were losing brake assist in the 2023 Cadillac Lyriq battery-electric crossover. Drivers said they experienced a hard brake pedal, followed by a “Brake System Failure” message at startup or while driving. GM shared records about its own internal investigations into “loss of brake assist due to alleged spindle fractures in the eBoost system.”
GM’s eBoost is an electronic brake-by-wire system that replaces traditional mechanical linkages between the pedal and braking mechanism. In the event of a spindle fracture, anti-lock brakes, stability control, and traction control remain functional until the vehicle comes to a complete stop, GM told the safety agency.
“At this point, ABS, brake assist, stability control, and traction control functions are lost.”
2025 Cadillac Lyriq front 3/4 angle in blue while chargingCadillac
Malfunction Lights In Gauge Cluster
With failed performance of the Electronic Brake Control Module (EBCM), the vehicle would then display one of three Diagnostic Trouble Codes (DTCs), which then activate these driver alerts: an audible chime, a visual “Service Brake System” message, and multiple malfunction lights in the gauge cluster for the ABS, traction control, and brakes.
Drivers on the highway will definitely know something is amiss because vehicle speed will be limited to 43 mph – basically limp-home mode. Since opening the 2024 inquiry, the ODI has continued receiving reports of lost brake assist, and the symptoms are inconsistent with GM’s description of a spindle failure.
2026 GMC Canyon AT4X driving front 3/4 gravel off-roadGMC
“These reports allege an immediate loss of brake assist functionality as opposed to the loss occurring after the vehicle comes to a complete stop.”
Six Injuries Reported, No Deaths
The agency says this loss could result in extended braking distances, increasing the risk of a crash or injury; further analysis is underway to assess the potential for failures in GM’s eBoost system and resulting accidents.
The investigation has now expanded to every GM brand. These GM vehicles equipped with the eBoost system could be impacted:
2023-2026 Cadillac Lyriq
2024-2026 Chevrolet Traverse
2025-2026 Cadillac Celestiq
2023-2026 GMC Canyon
2025-2026 Cadillac Optiq
2024-2026 GMC Acadia
2023-2026 Chevrolet Colorado
2024-2026 Buick Enclave
2024-2026 Chevrolet Blazer EV
2024-2026 Buick Envision
2024-2026 Chevrolet Equinox EV
2024-2026 Cruise Origin
2024-2026 Acura ZDX
2024-2026 Honda Prologue
The ODI calls this an “Engineering Analysis,” which is being expanded to encompass all GM vehicles using eBoost. The investigation number is EA26006 for those who wish to visit the NHTSA.gov website for more information.
CarBuzz Insight – Why This Matters:
NHTSA is investigating 745 incidents tied to GM’s eBoost technology, and the ODI is focusing on 227 of them for now. Of those, 21 resulted in crashes or fires and six resulted in injuries. There have been no related fatalities. If you’re one of the 1,164,820 Americans driving one of the above vehicles, it’s cause for concern, but the problem has not yet been elevated to a full-blown recall and there are no do-not-drive recommendations at this point to park your car until it can be checked out.
Source: NHTSA
