GM Service Manual Online
For 1990-2009 cars only

For a view of the oil flow diagrams, refer to the 1996 TURM Manual.

When the selector lever is moved to the Reverse (R) position, the manual valve is repositioned in order to allow the line pressure to enter three passages:

    • Reverse
    • RNDI (Reverse, Neutral, Drive, and Intermediate)
    • RND (Reverse, Neutral, and Drive)
    • Reverse oil from the manual valve performs the following functions:
        1. It seats the direct clutch and reverse checkball in the direct clutch passage
        2. It flows to both the inner and the outer areas of the clutch piston, applying the direct clutch
        3. It seats the Lo and Reverse checkball in the Lo First passage
        4. It applies the Lo and Reverse clutch
        5. It flows to the reverse boost valve and will boost the reverse line pressure to about 827 kPa (120 psi)
    • RNDI oil from the manual valve flows to the throttle valve and is regulated to TV pressure. TV oil flows through the shift TV valve and is limited by the valve to approximately 620 kPa (90 psi).
        Oil from the shift TV valve is directed to the TV boost valve. Shift TV oil acts on the TV boost valve in order to boost reverse line pressure to approximately 1447 kPa (210 psi).
    • RND oil from the manual valve is directed to the 2-3 shift valve, but this has no function in Reverse.

Summary

The direct clutch is applied. The Lo and Reverse clutch is applied. The transmission is in Reverse (R).