Subaru XT 1988 Service Manual page 1263

BODY ELECTRICAL SYSTEM
3) Actuator
The diaphragm is operated by vacuum or atmospheric pressure
led by each valve, and this diaphragm movement actuates the
wire cable via link ASSY to open or close the throttle valve.
With the cruise control set to OFF (system OFF state), no dia-
phragm operation occurs as the atmospheric pressure is kept
inside the actuator.
4) Engine throttle
The throttle body is equipped with two throttle cams. One
cam is used during acceleration and the other during cruising,
in order to open or close the throttle valve. These cams
operate independently of each other. In other words, while
one cam is operates, the other does not.
System OFF
Accelerator cable
Cam (Accelerator)
Throttle body
Cam (Cruise control)
System ON Accelerator cable
Cam (Accelerator)
Cam (Cruise control)
Fig.
83
53
To accelerator pedal
Atmospheric pressure
Actuator cable
To accelerator pedal
..
-=-••
~
Vacuum pump
Actuator
6-2
L6-1505