I do not recall reading or hearing of passenger cars going to the Oahu or the military in Hawaii during the war. In the 1930s the Oahu R&L had converted excess passenger cars to light-weight freight service, like moving cans to the canneries. These were converted back during the war to meet the needs for carrying civilian commuters and service men between Pear Harbor and Honolulu at the shift changes.
The freight cars were needed for transporting the increased flow of goods between the freight wharves. warehouses and other storage/use locations. Also to and from the ammunition depots.
Brian Norden