Throttle Valve Linkages
The throttle valve (TV) cable connects the movement
of the throttle pedal movement to the throttle valve in the
transmission’s valve body. On some transmissions, the TV
linkage may control both the downshift valve and the
TV. Others use a vacuum modulator to control the TV
and a throttle linkage to control the downshift valve.
Late-model transmissions may not have a throttle cable.
Instead, they rely on electronic sensors and switches to
monitor engine load and throttle plate opening. The
action of the TV produces throttle pressure. Throttle
pressure is used as an indication of engine load and influences
the speed at which automatic shifts take place.