DESCRIPTION
The 4L80-E transaxle uses 2 electric shift solenoids to control transmission upshifts and downshifts. In addition, a force motor (solenoid) controls hydraulic line pressure, and a Torque Converter Clutch (TCC) solenoid controls TCC application. Solenoid is turned on and off by the Powertrain Control Module (PCM) or Transmission Control Module (TCM). The PCM/TCM has on-board self-diagnostics to help identify any parts or circuits that may need further testing.
Note. For testing information on converter clutch lock-up control, see AUTO TRANS DIAGNOSIS - GM TORQUE CONVERTER CLUTCH .
OPERATION
Shift solenoid holds hydraulic pressure when is on and releases pressure when it is off. This action controls the shift valves inside valve body. By switching one or both solenoids on or off, different combinations of clutches, sprags and bands are operated. See CLUTCH & BAND APPLICATION CHART table under ELECTRONIC TESTING.