2024 Cadillac Lyriq

On August 9, 2026, at approximately 3:40 a.m., while driving, the vehicle suddenly lost all propulsion and became completely disabled on the roadway. The vehicle remained powered on but would not move forward or backward. At approximately the time of the failure, Cadillac/OnStar Advanced Diagnostics generated a critical Electric Drive Unit warning instructing immediate service and reported diagnostic code P0A78. Additional vehicle diagnostic warnings involved the electric drive unit/high-voltage propulsion system. I immediately contacted roadside assistance but was unable to obtain a workable towing solution for several hours. The vehicle ultimately had to be privately towed and has remained undriveable since the incident. The loss of propulsion occurred unexpectedly while the vehicle was being driven, without advance warning that would have allowed me to safely plan for the vehicle to become disabled. I am concerned that the same sudden loss of propulsion could occur at higher speed, in traffic, at an intersection, or in another location where an unexpected loss of motive power could create a serious crash risk. The vehicle requires diagnosis and repair for the Electric Drive Unit/P0A78 condition.

My 2024 Cadillac LYRIQ generated the following High Voltage Battery fault codes via On-Demand Diagnostic: U2B4A, U2B4D, U2B50, U2B53, U2B56, U2B59, U2B5C, U2B5F, U2B62, U2B65, U2B68 — all under module VIC - Lithium-Ion Battery. Multiple codes are flagged "Service Right Away" indicating an active fault in the high voltage propulsion battery system. I brought the vehicle to Lindsay Cadillac, Alexandria VA [XXX] ) on [INSERT DROP-OFF DATE]. As of today [INSERT TODAY'S DATE], the vehicle has been sitting at the dealership for [X] days with ZERO repair action taken. The service manager has stated he does not know what to do, has no timeline, and cannot provide any answers. GM Technical Service Bulletins PIP6009B and 25-NA-044 specifically cover these exact DTCs and provide a documented repair procedure. The dealer has failed to follow or initiate this procedure. No loaner vehicle was provided despite this being a warranty repair on inoperative vehicle. I have been forced to rent a vehicle at $125/day out of pocket. I have an open Cadillac Concierge case number [93707662 #]. Cadillac Concierge was unable to reach the dealer's service department by phone. I have escalated in writing to GM's executive office including [XXX] and [XXX] with no resolution. This is a high voltage battery fault on an all-electric vehicle flagged as "Service Right Away" severity. The vehicle remains unrepaired, the dealer is unresponsive, and GM's own customer service cannot reach the dealer. This represents both a safety concern and a complete failure of the warranty service obligation. I am requesting NHTSA investigation of both the underlying battery defect and the dealer's failure to act on a known TSB. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

While driving in one-pedal driving mode at the high setting, an error message appeared and one-pedal driving suddenly shut off and switched to a more standard drive mode where engine braking is disengaged. This happened while drive was engaged and stopped at a red light. The car briefly lurched forward and the car engaged an emergency brake to prevent the car from rolling into the vehicle in front of me. This incident was unpredictable and resulted in an unexpected change to the drive mode I had selected which could have lead to a collision.

While driving my 2024 Cadillac Lyriq in rolling traffic, the vehicle abruptly engaged the brakes without warning or cause. The braking was so forceful I initially thought I had been rear-ended. Once the braking event ended, I began to accelerate—only to discover the vehicle had shifted into reverse without any input from me. This resulted in a rear-end collision. There were no alerts or dashboard warnings to indicate the gear change. I believe this may be related to a malfunction in the automatic emergency braking system or the shift-by-wire controller. This behavior presents a serious safety hazard and must be investigated. I have filed a report with Cadillac and will be taking the vehicle to a dealership for diagnostics and data log review.

While driving northbound on [XXX], south of Oklahoma City, at normal highway speed, at night, in the rain (on [XXX]), this EV lost all power to the wheels and the regenerative braking ceased to function. It appears that all flow of electrons from the batteries to the drive motors, and from the regenerative brakes to the batteries stopped. I still had dashboard lights, steering, and conventional brakes. I was able to safely coast to a stop on the highway shoulder. I set the parking brakes, put the “transmission” into “park”, and turned off the power button. I then restarted the car, and all was normal again. I continued my drive from Austin, TX, to Evergreen, CO with no additional incidents, arriving on [XXX]. This is reminiscent of the “blue screen of death” in old Microsoft desktop computers — fixed the problem by cycling the ON / OFF switch. Unfortunately, doing this when driving at 75 mph is less than ideal, and is a real potential safety problem. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)