The accumulation of moisture at major connectors and control units can cause various ABS/PDAS faults due to corrosion.Google+
Car Problem Reports
Porsche 911 Turbo ABS Light On Due to Moisture and Corrosion
Porsche 911 Turbo Problem
Visitor, 1992 Porsche 911 Turbo, 200,767 mi
ABS light on - found corrosion after having the car in South Carolina monsoons.. it took me awhile though.. you know the connector comes apart and the pins can be removed/replaced, ... Love German engineering...
Oh, the running gear has been rebuilt and the engine rebuilt/upgraded.. so, don't laugh at the mileage. it'll never be a collector so I choose to dirve it..