GM Service Manual Online
For 1990-2009 cars only

Condition

Possible Cause

No engine braking or 3-2-1 manual downshift

    • Shift select cable out of adjustment, binding or damaged
    • Manual valve binding or sticking
    • 2-3 shift valve binding or sticking
    • 1-2 shift valve binding or sticking
    • Primary regulator valve binding or sticking
    • Broken or distorted valve springs
    • Damaged or porous valve body casting
    • Intermediate servo piston binding or sticking
    • Intermediate servo piston seals cut or damaged
    • Intermediate servo piston rod binding
    • 2nd brake band worn or out of adjustment
    • 1st-reverse brake clutch discs worn
    • 1st-reverse brake piston or seal leaking or damaged
    • One-way clutch not holding or damaged