I found two bulletins:
PIT5481D 20 August 2018
PIT5481C 19 January 2018
I don't know if these are GM actual bulletins or NTSB...
This PI was superseded to update the models and model years. Please discard PIT5481C.
This PI is to provide additional information on the functionality of Lane Keep Assist and also to help understand why some customers may comment they do not get alerts (audible chime or safety alert seat vibration) when they cross a lane marker.
Lane Keep Assist (RPO UHX) replaced Lane Departure Warning (RPO UFL) starting with the 2016 model year. Lane Keep Assist is designed to assist the driver in keeping the vehicle from drifting out of a driving lane that has clearly identified markings. The electric power steering provides a gentle steering correction if a lane marking has been crossed and the driver has NOT actively responded (i.e. steering, accelerating, braking, use of turn signal). In situations where the steering corrections does not keep the vehicle from crossing the lane marker and the driver has NOT actively responded (ie. steering, accelerating, braking, use of turn signal), the Lane Departure Warning may activate and provide an alert (chime or safety alert seat vibration) back to the driver. If the driver tries to "test" the Lane Departure Warning alert and over comes the Lane Keep Assist correction so the vehicle intentionally crosses the lane marker, the system may interpret this as an active response, and in many cases, the system will NOT provide an alert. Therefore, alerts do NOT occur as often with Lane Keep Assist when compared to the Lane Departure Warning system used in the previous model year vehicles.
For Lane Keep Assist to start providing assist, the following criteria must be met:
Vehicle speed between 38 mph and 111 mph
Lane markings are clearly visible
Lane Keep Assist is turned "on" via the enable/disable button located on the dash. When enabled, the LED on the button will illuminate.
Lane marker width meets Lane Keep Assist criteria (not too wide or narrow)
Lane marker radius meets Lane Keep Assist criteria (curve is not too tight)
When the criteria listed above is met, the Lane Keep Assist icon will illuminate, as seen in the photo below.
Object ID: 4319175Click here for detailed picture of the image.
The Lane Keep Assist icon has several different indication modes:
Solid green indicates the system is ready to assist.
Solid amber indicates Lane Keep Assist intervention is occurring
Flashing amber indicates a Lane Departure Warning alert (chime or safety seat vibration)
Lane Keep Assist and Lane Departure Warning alerts are suppressed with any deliberate driver response (ie. steering, accelerating, braking, use of turn signal, see below)
Drivers can suppress/override Lane Keep Assist with the following deliberate maneuvers
Turning the steering wheel
Turn signal is on in the direction of the lane crossing
Proper operation may be affected by factors outside the vehicle, including:
Nearby vehicles ahead (tailgating)
Sudden lighting changes, such as going through a tunnel
Poor lane markings, such as on some two-lane roads
Snow, frost, ice, dirt, mud, bugs, etc on the windshield that are blocking the front camera
Tar marks, cracks, shadows, temporary lane markings and other road imperfections
Lane markings on one side of the road only (Lane Keep Assist provides assist only on the side with markings).
The driver is advised to turn off the system when these conditions are present; this does not indicate a system failure.
In addition, do not use Lane Keep Assist while towing a trailer or on a slippery road, as this may cause a loss of vehicle control.
Thats all it says on that one