The CORRECT wiring diagram for that tractor is determined by the serial number of the tractor. A TRUE wiring diagram is found in the correct Operator's Manual for that tractor and that diagram shows the wire colours. Generic wiring diagrams can lead you down the garden path and frustrate the diagnosis of the problem. The 446 was made from 1972 to 1988 and changes in the wiring took place over that 16 year period.
The link below will transport you to a site that hosts many of the Operator manuals that pertain to Case and Ingersoll tractors.