A/T - 4L80E Neutral Feel On 3-4 Upshift
DATE: 1996TECHNICAL BULLETIN # 333
TRANSMISSION: 4L80-E
SUBJECT: Neutrals on the 3-4 upshift
APPLICATION: GM Trucks
4L80-E
This symptom may be caused by a leak in the solenoid B circuit. It is not uncommon for the feed circuit for shift solenoid B to supply too little oil. When this happens, and solenoid A closes for the shift to fourth, solenoid B pressure can not continue to hold the 1-2 shift valve in the shifted position. The transmission is actually making a 1-2-3-1 shift which feels like neutral.
Note:
Because the computer still commands fourth gear when the manual lever is in manual third, this condition will still occur in manual third.
If the leak cannot be found (damaged solenoid B o-ring, solenoid B doesn't close fully when energized, etc.) drill the shift solenoid B feed orifice to .035"-.041".