[cellsafemode]

almost sounds like you guys got a kind of dealer installed jerry rigged version of ambient lighting.

Where instead of using the hmi to control the lighting, you have an entirely separate module that either works on mechanical switch or listens to ODB2 and triggers on the drive mode change state.

This would make it cheaper than having to program the HMI probably. And it would allow the addon (ambient lighting) to be installed much more readily at the dealer's discretion without having to depend on GM updating their database of what is allowed to be flashed to your car's HMI.