GM Service Manual Online
For 1990-2009 cars only

When the gear selector lever is moved to the MANUAL SECOND range (2), the manual valve (404) allows line pressure to enter the D2 passage. D2 fluid seats the #8 checkball (3721). D2 fluid is directed to the 2-3 shift valve (357) in order to shift the valve. When shifted, D2 fluid enters the manual 2-1 servo feed passage and strokes the manual 2/1 servo assembly (104-116) in order to apply the 2/1 band (680). The third clutch is released by allowing third clutch/Lo-First applied fluid to exhaust by seating the #4 checkball (372) against the Lo-First passage and into the third clutch passage. Third clutch fluid is then directed to the #9 checkball (372). The fluid seats the checkball against the third fluid passage, forcing the fluid through an exhaust orifice into the third fluid passage. Third fluid is then sent to the 2-3 shift valve (357) where the fluid exhausts. Since D2 fluid overrides line pressure at the 2-3 shift valve (357), a manual 3-2 downshift will result even if the 2-3 shift solenoid valve is de-energized (turned OFF). The normal DRIVE range Third gear solenoid state is as follows:

    • 1-2, 3-4 shift solenoid valve - OFF
    • 2-3 shift solenoid valve - OFF

If the PCM receives the appropriate input signals from the VS Sensor and the TP Sensor, the 2-3 shift solenoid valve will energize (turn ON). The 2-3 shift solenoid fluid is then directed to the 4-3 manual downshift valve (360) and to the 3-2 manual downshift valve (356).

Manual Valve (404)

The gear selector lever moves the manual valve, allowing line pressure to enter the D2 passage.

#8 Checkball (372)

The #8 checkball is located in the valve body (300). The checkball is fed D2 fluid from the manual valve (404). The checkball then directs the fluid to the 2-3 shift valve (357).

2-3 Shift Valve (357)

When shifted by D2 fluid, the 2-3 shift valve allows D2 fluid to enter the manual 2-1 servo feed passage in order to stroke the manual 2/1 servo assembly (104-116). This allows third fluid to exhaust.

Manual 2/1 Servo Assembly (104-116)

The manual 2/1 servo assembly applies the 2/1 band (680) during MANUAL SECOND and MANUAL FIRST gear ranges.

#4 Checkball (372)

The #4 checkball is located in the channel plate (400). The checkball directs third clutch/Lo-First exhaust fluid into the third clutch passage.

2-3 Shift Solenoid Valve (315)

An energized 2-3 shift solenoid valve allows line pressure to enter the 2-3 shift solenoid valve passage. The valve then sends the fluid to the 4-3 manual downshift valve (360) and to the 3-2 manual downshift valve (356). However, this event does not have to occur in order to achieve a manual 3-2 downshift.

3-2 Manual Downshift Valve (356)

The 2-3 shift solenoid valve fluid shifts the 3-2 manual downshift valve. This action prevents the 2-3 shift valve (357) from upshifting.

Drive Range, Manual 2nd (from Drive, Manual 3rd)


Object Number: 350387  Size: FS
Solenoid Valve
Torque Converter Clutch Pulse Width Modulation Solenoid Valve (TCC PWM Sol. Valve)
Solenoid Valve
Solenoid Valve