GM Service Manual Online
For 1990-2009 cars only

When the gear selector lever is moved to the Manual Second (D2) gear range, the manual valve moves and allows line pressure to enter the D2 fluid passage. The transmission reacts by shifting immediately into second gear range and is prevented from upshifting into either Third or Fourth gear.

Manual Valve (404)

Is moved by the gear selector lever allowing line pressure to enter the D2 passage.

Number 8 Ball Check Valve (372)

Located in the control valve body (300), is fed D2 fluid from the manual valve (404) and directs it to the 2-3 shift valve (357).

2-3 Shift Valve (357)

When shifted by D2 fluid, it allows D2 to enter the manual 2-1 servo feed passage to stroke the manual 2-1 servo assembly (104-115) and allows 3rd fluid to exhaust.

Manual 2-1 Servo Assembly (104-115)

Applies the manual 2-1 band (680) during manual second and manual first gear ranges.

Number 4 Ball Check Valve (372)

Located in the case cover (400), it directs 3rd clutch/lo-1st exhaust fluid into the 3rd clutch passage, releasing the 3rd clutch.

2-3 Shift Solenoid (SS) Valve (315)

When energized, it allows line pressure to enter the 2-3 signal fluid passage and sends it to the 4-3 manual downshift valve (360) and 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)

Is shifted by 2-3 signal fluid and prevents the 2-3 shift valve (357) from upshifting.

Transmission Fluid Pressure (TFP) Manual Valve Position Switch

D2 fluid is routed to the TFP manual valve position switch. The TFP manual valve position switch signals the PCM that the manual valve is in the Manual Second position.

Pressure Control (PC) Solenoid

The PCM increases the PC solenoid duty cycle to increase the operating range of torque signal fluid pressure in Manual Second. This provides increased line pressure for the additional torque requirements during engine compression braking and increased engine load in Manual Second.

Torque Converter Clutch

The PCM will release the TCC before downshifting into Manual Second. The TCC will not re-apply in Second gear under normal operating conditions.

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


Object Number: 768848  Size: FS
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)