940 L4-2.3L SOHC VIN 88 B230F (1992)
4th Gear Only
The signal valve moves downwards when the governor pressure B is sufficiently high (i.e. when the car is driven above a certain speed).
This admits line pressure D to the underside of the changeover valve, which moves upwards and permits oil to flow to the torque converter in
the opposite direction. This forces the lock-up clutch plate into contact with the friction lining on the housing, eliminating slip. Since the oil in
the torque converter is now almost at rest, it does not require to be cooled.