The 2-3 shift is a result of the band releasing and the 3-4 clutches applying. What happens when the band releases and the 3-4 clutch are not yet applied (excess clearance) you get a neutral position normally refered to as a flare.Once the flare starts it is just a short amount of shifts before the clutches become glazed and will not hold.

Transmission temperature plays a HUGE roll in how long the 3-4 clutches will last. When the temperature increases the fluids viscosity becomes a lot thinner. The thinner viscosity fluid will not allow as much pump pressure and the amount of fluid leakage around the seals and sealing rings increase causing less pressure and slower apply of the 3-4 clutches.

Low transmission fluid will quickly destroy the 3-4 clutches. The transmission will use the entirity of the fluid volume to apply the the forward clutch and band. When the fluid releases the band and when the 3-4 piston goes to apply the pump will cavitate and there will not be enough holding pressure on the 3-4 clutch. With only as much as 1-1 1/2 quarts will cause this.I hear about it all of the time.

Line pressure is controled by the EPC solenoid (Electronic Pressure Control). The EPC is a solenoid that dumps off line pressure and is controled by varying the amount of current going to it by the PCM. The PCM controls the EPC based on several factors. One factor being the input of the TPS sensor. At WOT the PCM is keeping the line pressure at max which keeps the clutches applying fast and hard. Lets say for example a 700RWHP C5 is street driving and at 1/2 throttle is still making 300-400RWHP but the EPC is dumping off line pressure. This has to be done to keep part throttle shifs comfortable but is hard on the clutch/band life. What I am saying is that a C5 that is tracked only 100% TPS will live longer than a street driven C5 that sees a lot of part throttle action. Proper tuning and ramping of the line pressure will help in this scenario.

Condition/Concern:
The 4L60E/4L65E may experience an intermittent neutral condition while accelerating from a stop (category one) or while driving (category two).

Category One: Intermittent neutral condition occurs on accel from a stop with the shifter in D4. The neutral may be associated with an engine flare and then a harsh engagement. The Transmission Fluid Pressure Switch should read correct signal "A" High "B" Low "C" Low.

Category Two: Intermittent neutral occurs during 2-3 shift and the transmission will not have 3rd or 4th gear. The "B" Shift Solenoid is not bleeding off during the 2-3 shift allowing the transmission to stay in 2nd gear and return to first during the 3-4 shift.

Recommendation/Instructions:

Category Two:

Attempt to duplicate the condition.

The "B" Shift Solenoid should be air checked for being restricted and not exhausting. However air testing the solenoid may remove the restriction. The "B" Shift Solenoid should be replaced.