Converter clutch engagement in third or fourth
gear range is controlled by sensor inputs to the powertrain
control module. Inputs that determine clutch
engagement are: coolant temperature, engine rpm,
vehicle speed, throttle position, and manifold vacuum.
The torque converter clutch is engaged by the
clutch solenoid on the valve body. The clutch can be
engaged in third and fourth gear ranges depending
on overdrive control switch position. If the overdrive
control switch is in the normal ON position, the
clutch will engage after the shift to fourth gear, and
above approximately 72 km/h (45 mph). If the control
switch is in the OFF position, the clutch will engage
after the shift to third gear, at approximately 56
km/h (35 mph) at light throttle.
