Adapt Function

The 4T80-E transmission uses a line pressure control system, which has the ability to continuously adapt the system's line pressure. This compensates for normal wear of the following parts:
^ The clutch fiber plates
^ The seals
^ The springs

The Powertrain Control Module (PCM) maintains the following adapt parameters for the transmission:
^ Upshift Adapt - The PCM monitors the Automatic Transmission Input (Shaft) Speed Sensor (A/T ISS) and the Vehicle Speed Sensor (VSS) during commanded shifts in order to determine if a shift is occurring too fast or too slow. The PCM adjusts the signal to the transmission Pressure Control (PC) solenoid valve in order to maintain a set shift feel.
^ Steady State Adapt - The PCM monitors the A/T ISS and the VSS after a shift and the PCM calculates the amount of slippage in that gear. The PCM then adjusts the signal to the transmission PC solenoid valve in order to maintain slippage below a set amount.
^ Garage Shift Adapt - The PCM monitors the A/T ISS during a shift into a given range (P,R,N,D) and the PCM calculates whether the engagement is occurring too fast or too slow. The PCM adjusts the PC solenoid valve in order to maintain a set shift feel.
^ Wide Open Throttle (WOT) 1-2 Adapt - The PCM monitors the VSS and the engine rpm during a 1-2 Wide Open Throttle (WOT) shift. The PCM will adapt the 1-2 shift point during WOT.
^ Learn Tap - Accelerated PLM learn mode. A technician must road test the vehicle for 15 minutes (normal time 2 - 3 hrs).

Transmission adapts must be reset whenever the transmission is overhauled or replaced. In order to reset transmission adapts, select the following:
1. Scan tool
2. Miscellaneous test
3. Automatic Transmission (A/T) outputs
4. Clear or reset all adapts

IMPORTANT: The transmission may experience harsh, soft or mushy shifts for up to two days later.