Chevrolet Equinox Service Manual: Transmission Adaptive Functions Automatic Transmission Unit

The 6T30/40/45/50 transmission utilizes a line pressure control system during upshiftsto compensate for the normal wear of transmission components. As the apply componentswithin the transmission wear or change over time, shift time (the time required toapply a clutch) increase or decreases. In order to compensate for these changes, thetransmission control module-(TCM) adjusts the pressure commands to the various PCsolenoids,to maintain the originally calibrated shift timing. The automatic adjusting processis referred to as “adaptive learning” and it is used to ensure consistent shift feelplus increase transmission durability. The TCM monitors the A/T input speed sensor-(ISS)and the A/T output speed sensor-(OSS) during commanded shifts to determine if a shiftis occurring too fast (harsh) or too slow (soft) and adjusts the corresponding pressurecontrol-(PC) solenoid signal to maintain the set shift feel.

The purpose of the adapt function is to automatically compensate the shift qualityfor the various vehicle shift control systems. The adapt function is a continuousprocess that will help to maintain optimal shift quality throughout the life of thevehicle.