Overdrive Range, Second Gear. GMC Truck Export Savana 2000

For 1990-2009 cars

In order to obtain second gear, the PCM receives input signals from the transmission speed sensors (input and output), the Throttle Position (TP) Sensor, and from other engine sensors. These signals determine when to de-energize the 1-2 Shift Solenoid (SS) Valve.

Manual Valve: In the Overdrive range second gear, line pressure from the pressure regulator valve is directed as PRND4, PRND43, and Drive fluid pressures. The PRND4 fluid pressure is directed to the Automatic Transmission Fluid Pressure (TFP) Manual Valve Position Switch Assembly and to the 2-3 shift valve. The PRND43 fluid is directed to the TFP manual valve position switch and to the manual 2-1 band servo. The Drive fluid is directed to the TFP manual valve position switch, the forward clutch, the 1-2 shift valve, and the accumulator valve.
Automatic Transmission Fluid Pressure (TFP) Manual Valve Position Switch Assembly: Drive, PRND4, and PRND43 fluid pressures from the manual valve are directed to the DR, PRND4, and the PRND43 switches on the TFP manual valve position switch. This sends a signal to the PCM that the transmission is in Overdrive range.
1-2 Shift Solenoid (1-2 SS) Valve: When the 1-2 SS valve is de-energized, 1-2 signal fluid exhausts through the solenoid. A spring force holds the 1-2 shift valve to the extreme right.
2-3 Shift Solenoid (2-3 SS) Valve: When the 2-3 SS valve is de-energized, 2-3 signal fluid pressure forces the 2-3 shift valve to the extreme right against a spring force.
1-2 Shift Valve: Spring force holds the 1-2 shift valve to the extreme right. Drive fluid pressure from the manual valve changes into 2-3 drive fluid pressure at the 1-2 shift valve. This pressure is directed to the 2-3 shift valve, to the TCC PWM Solenoid Valve, and to the intermediate (second) clutch.
2-3 Shift Valve: Spring force holds the 2-3 shift valve to the extreme right. The 2-3 drive fluid pressure from the 1-2 shift valve changes into Front Band Apply (FBA) and is directed to the manual 2-1 band servo. The PRND4 fluid pressure from the manual valve is held at the 2-3 shift valve in order to be utilized in other gear ranges.
3-4 Shift Range: Spring force holds the 3-4 shift valve to the extreme right.
Forward Clutch: Drive fluid pressure from the manual valve applies the forward clutch.
Intermediate (Second) Clutch: Second fluid pressure from the 1-2 shift valve applies the intermediate clutch. The 2-3 drive fluid pressure from the 1-2 shift valve seats the #4 checkball, causing the fluid to flow through two orifices and into the center support. This applies the Intermediate (Second) clutch. The 2-3 drive fluid pressure changes into Second apply fluid pressure at the orifices.

#### Overdrive Range, Second Gear

Control Valve Body Fluid Passages (Case Cover Side)
Control Valve Body Fluid Passages (Case Cover Side)
Control Valve Body Fluid Passages (Case Cover Side)
Control Valve Body Fluid Passages (Case Cover Side)
Control Valve Body Fluid Passages (Case Cover Side)
Control Valve Body Fluid Passages (Case Cover Side)
Case Cover Fluid Passages (Control Valve Body Side)
Case Cover Fluid Passages (Control Valve Body Side)
Case Cover Fluid Passages (Control Valve Body Side)
Case Cover Fluid Passages (Control Valve Body Side)