Here's my guess
I doubt it is a warning.....probably only in AWD vehicles with 2WD as an option to prevent novices from seizing of the engine due to overheating. There is no temperature sensor in the rear axle so it obviously feeds off excessive engine and transaxle temperatures. Difference being that AWD vehicles without the ability to convert to 2WD must remain in AWD even when the engine is overheating, but the AWD/2WD switchable vehicles can disconnect the additional engine load of the rear axle in an attempt to lower engine temperatures to a safe limit. No sense putting a notification message in a full time AWD since they are SOL and lack the ability to freewheel the rear axle to reduce engine/transaxle loading. And running full time AWD in an AWD/2WD you will never get the notification message under normal operating conditions.
Something akin to a comparing a cargo plane to a passenger plane in a situation desperately in need of additional altitude sufficient to clear a mountain range.....the cargo plane has the ability to dump the cargo and reduce loading to safely complete the trip, but the passenger plane is SOL.
Current Chevys -'16 Silverado LT;'18 Malibu LT Redline;'18 Traverse Premier Redline<br /><br />Previous Chevys:16 Malibu LT2 '17 Impala;'16 MalibuLT;'15 Camaro LS;'15 Traverse; '13,'12 and '07 Avalanche LTs; '11 Tahoe LT; '13 &'11 Malibu LTs; '08 Trailblazer;'06 Colorado WT..... Chrysler era.....'80 Citation;'75 Impala;'72 Chevelle;'69 Camaro R/T;'65 Impala SS;'62 Nova