For a view of the oil flow diagrams, refer to the 1996 TURM
manual.
Use Manual First for maximum engine braking when the car is descending
steep grades. Select Manual First at any vehicle speed. However, the transmission
will first downshift into Manual Second. The transmission will later downshift
to Manual First when the vehicle is at a specified speed according to vehicle
application.
Manual Valve: In the Manual First range, line pressure from the pressure regulator
valve is turned into Drive, D321, D21, and Low fluid pressures. The Drive
fluid pressure is directed to the forward clutch. The D321 fluid pressure
is directed to the overrun clutch. The D21 fluid pressure is directed to the
2-3 shift valve. The Low fluid pressure is directed to the Automatic Transmission
Fluid Pressure Manual Valve Position Switch (TFP Val. Position Sw.) Assembly
and to the rear servo.
Automatic Transmission Fluid Pressure Manual Valve Position Switch (TFP
Val. Position Sw.) Assembly: Low Fluid pressure from the manual valve is directed to the Low pressure
switch on the TFP Val. Position Sw. assembly. This sends a signal to the Powertrain
Control Module (PCM) that the transmission is in Manual First. Drive fluid
pressure is also supplied to the TFP Val. Position Sw. Assembly.
1-2 Shift Solenoid (1-2 SS) Valve: When the 1-2 SS Valve is energized, signal A fluid pressure forces the
1-2 and the 3-4 shift valves to the extreme left.
2-3 Shift Solenoid (2-3 SS) Valve: When the 2-3 SS Valve is de-energized, signal B fluid pressure exhausts
through the solenoid.
1-2 Shift Valve: Signal A fluid pressure holds the 1-2 Shift Valve to the extreme left.
The actuator feed and the drive pressures supplied to the 1-2 shift valve
are blocked.
2-3 Shift Valve: Spring pressure and the D21 fluid pressure from the manual valve hold
the 2-3 Shift Valve to the extreme right.
3-4 Shift Valve: Signal A pressure forces the 3-4 Shift Valve to the extreme left.
Rear Servo: Low fluid pressure from the manual valve is directed to the #7 checkball
and to the rear servo, which applies the rear band. Low fluid
pressure changes to Rear Band Apply (RBA) fluid pressure at the checkball.
Forward Clutch: The forward clutch is applied by Drive fluid pressure from the manual
valve.
Overrun Clutch: The D321 fluid pressure from the manual valve seats the #1 checkball
in the case. This causes the fluid to flow through an orifice, where the D321
fluid pressure changes into overrun fluid pressure. The overrun fluid pressure
flows through the case and the pump housing, and into the overrun clutch housing,
which applies the overrun clutch. The overdrive roller clutch becomes ineffective
and provides vehicle engine compression braking.