u/johnb_123

Title basically. The updates are flowing but it seems the same to me.

I previously had a Mustang Mach E with bluecruise and they did some noticeable improvements I don’t yet see in Supercruise.

for example, inching over when you’re next to a big rig. Likewise, bluecruise will often bias slightly away from concrete barriers or guardrails. It’s a small movement, but it made that system feel much more refined. That was in 2023.

Three years later, missing from Supercruise…which is somehow higher rated than most other ADAS on the market.

>!I’m curious whether other Lyriq owners, or owners of related Ultium vehicles (Blazer EV, Equinox EV, Prologue, ZDX), have experienced something similar.!<
>!A few weeks ago my 2024 Lyriq displayed a “Service High Voltage System” warning. I took it to the dealer. They found a historical P1C26 code but could not reproduce the issue. Their notes referenced an A/C refrigerant high-side pressure sensor and stated that everything was reading normally at the time of inspection. They basically reset the code and sent me on my way (1 week in the shop and several TAC calls later).!<

>!Fast forward to this week.!<
>!I was driving through Barstow (vegas to LA) in 106°F weather. The vehicle had been on the road for about two hours at freeway speeds, roughly 75 to 80 mph. I arrived at an Electrify America station at about 20% SOC.!<

>!The charging session was unexpectedly!< >!slow!<>!.!<

>!The vehicle would not charge above roughly 35 to 40 kW. I tried multiple EA dispensers and received essentially the same result. Electrify America checked the station remotely and told me the prior charging session on that equipment had been operating at normal speeds.!<

>!The next day, conditions were completely different. Ambient temperature was about 63°F. I charged at a Tesla Supercharger using the GM-approved NACS adapter. At approximately 50% SOC, charging started around 139 kW and then tapered into the 90 kW range by the mid-50% SOC range.!<

>!That has me wondering whether the original high-voltage warning and the poor charging performance in extreme heat might be related to the thermal management system rather than the battery itself.!<

>!A few questions:!<

>!Has anyone seen a P1C26 code?!<
>!Has anyone received a Service High Voltage System warning that was eventually traced to the A/!<C or thermal management system?
Has anyone experienced dramatically reduced DC fast charging speeds only during very hot weather?
If so, what was the eventual fix?

At this point the vehicle seems to charge normally in cooler conditions, which makes diagnosis a bit challenging. I’m mainly trying to determine whether this is a known Ultium platform issue or an isolated case.

Any experiences, service bulletins, or repair outcomes would be appreciated.