The icon showing a vehicle going down a steep slope is hill decent control. It comes on every time you turn the key from off to on. That is normal.

Since the light comes on first thing in the morning and then goes out it is more likely the system is losing pressure.

Suggest you start it up and measure as above, record the numbers by wheel and check again in the morning to see what changes. We can better troubleshoot with that information.

The slope should not cause the inactive warning to come on.

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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior
Dallas