No Third Gear - D4

WARNING: This page is about a different car, the 2006 GMC Yukon XL, 2006 Chevrolet Suburban, and 2006 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

No Third Gear - D4

Checks	Cause
Direct Clutch Components
Seal (620, 621, 622)	Leaking
Ball Check	Leaking
Piston (619)	Cracked or jammed
Housing (623)	Cracked
Reaction Plates (618)	Worn splines
Friction Plates (611)	Worn splines or worn friction
Spring Assembly (607)	Jammed
Center Support Seals (639)	The seals are leaking at the center support hub.
Center Support (640)	The support is broken or leaking at the case.
Center Support Bolt (25)	Loose or broken Blocked hole
2-3 Solenoid (311)	Stuck Off Pinched wire O-ring failure No voltage to the solenoid
PCM	No signal to the solenoid
2-3 Shift Valve (312)	Stuck
PCM	Failed
Check the PCM for current DTCs.