Drive Range, Manual 1ST (From Drive, Manual 2ND)

A manual 2-1 downshift is initiated by moving the gear selector lever to the Manual First (1) position. However, the transmission will not downshift into First gear until vehicle speed is below approximately 60 km/h (37 mph), At higher vehicle speeds the PCM will keep 1-2 shift solenoid (SS) valve de-energized (OFF) and the transmission will operate in Manual First - Second Gear. In Manual First the transmission is electronically prevented from upshifting into Third or Fourth gears under any conditions. Also, the third clutch is applied in Manual First - First Gear to provide engine compression braking.

Manual Valve (404)
Line pressure is routed into the Lo fluid circuit when the selector lever is moved into the Manual First (1) position. Line pressure continues to feed the D4, D3 and D2 fluid circuits as in Manual Second.

Transmission Fluid Pressure (TFP) Manual Valve Position Switch
LO fluid pressure is routed to the Transmission Fluid Pressure (TFP) manual valve position switch and the TFP manual valve position switch signals the Powertrain Control Module (PCM) that the manual valve is in the Manual First position.

Number 7 Ball Check Valve (372)
Located in the control valve body (300), directs Lo fluid to the 1-2 shift valve (318).

1-2 Shift Valve (318)
When shifted against spring force, allows Lo fluid to enter the Lo-1st passage to the pressure regulator valve (313). During release of the 2nd clutch exhausting 2nd fluid passes through the valv6 and enters the 3rd fluid passage.

Lo Blow Off Valve (407)
A relief valve that exhausts excess Lo fluid pressures above 448 kPa (65 psi) from the 3rd clutch apply circuit.

Number 4 Ball Check Valve (372)
Located in the case cover (400), it seats against 3rd clutch fluid allowing Lo-1st fluid to enter the 3rd clutch fluid passage and apply the 3rd clutch.

1-2, 3-4 Shift Solenoid (SS) Valve (315)
Energizes, allowing line pressure to feed into the 1-2, 3-4 signal fluid passage and to the 3-4 shift valve (362).

Number 2 Ball Check Valve (372)
Located in the case cover (400), forces exhausting 2nd clutch apply fluid through an orifice into the 2nd clutch passage and to the 1-2 shift valve (318).

Pressure Regulator Valve
Lo fluid is directed through the 1-2 shift valve (318) into the Lo-1st fluid passage. Lo-1st fluid is sent to the pressure regulator valve (313) to boost line pressure and at the same time to the Lo blow off valve (407). The addition of Lo-1st fluid pressure increases the operating range of line pressure in Manual First.