Overdrive Control

OVERDRIVE CONTROL
- The overdrive is controlled by the overdrive control switch located on the selector lever to provide shifts from "D3" to "D4" or vice versa.
- When the overdrive control switch is set to "ON", "D4" shift occurs.

Overdrive control switch in "ON":
The OD cancel solenoid valve is set in "OFF" and line pressure is drained. As a result, the 3-4 shift valve moves upward. When governor pressure acting on the lower end of the 3-4 shift valve exceeds the specified value, "D4" shift occurs.

Overdrive control switch in "OFF":
The OD release solenoid is set in "ON" and line pressure is directed to the upper end of the 3-4 shift valve. This moves the 3-4 shift valve downward. The 3-4 shift valve is held downward even when governor pressure increases. At this point, "D4" shift does not occur.