This function replacement unit mounts on back side of the tachometer.
When ground is received from the wiper switch, this unit blocks vacuum flow to the control side of the wiper relay valve, this in turn directs the main vacuum flow to the actuator which opens the door.
Will require the replacement of the dual terminal connector housing with 2 separate single housings (included). There is no wire cutting, simply transfer the 2 wires with terminals from the dual housing to the single ones.