They are all linked to the first ABS the two other systems Traction control I know defiantly and I would say probably hill descent use the same method of control as ABS, in other words when your using traction control it will lock and unlock wheels that loose traction to regain it.
I would imagine it’s an ABS sensor problem; check all the wheels are they mucky - try giving them a jet wash - it could clear it, even check your fluid level for starters.
