A/T - 4L80E Binds In Lo/Starts in 3rd Gear
TECHNICAL BULLETIN # 126TRANSMISSION: 4L80-E
SUBJECT: Bind in Low/3rd Gear Starts
APPLICATION: GM
A 4L80-E with a complaint of 3rd gear starts (regardless of electrical commands) accompanied by a bind-up in manual low may be caused by a broken dished cushion plate in the direct clutch. A broken cushion plate will mechanically apply the clutch which causes the complaints.
Be aware that a failed closed (clogged) solenoid B or a stuck 1-2 shift valve will cause 2nd gear starts and bind up in manual low.