No Fourth Gear

1. 2-3 shift valve stuck.
2. Solenoid B malfunctioning.
3. Quad driver module failure.
4. Overrun clutch reaction plates splines or sun gear worn.
5. Fourth clutch components:
a. Cup plug or bolt loose, broken or missing.
b. Piston or spring assembly jammed.
c. Seals nicked or cut.
d. Friction or reaction plates worn or burned.