Transmission Service Fast Learn Procedure
The transmission service fast learn is a procedure that is performed after any 8L45 transmission repair. The service fast learn procedure performs a series of tests which allow the transmission control module (TCM) to learn individual clutch apply pressures. These learn pressure values are used by the TCM for clutch control and timing of shifts. The scan tool is used to perform the transmission service fast learn procedure.
The service fast learn procedure must be performed when any of the following repairs has been made to the transmission.
- Pressure regulating solenoid replacement
- Valve body repair or replacement
- Any service/repair in response to a shift quality concern
- Any internal transmission service, repair, overhaul, or replacement
- TCM replacement
- Transmission assembly replacement
- Reprogramming Transmission Control Module
Failure to perform the procedure may result in poor transmission performance, DTCs being set, or customer dissatisfaction. Perform the service fast learn procedure in the exact sequence as listed below.
- If a pressure regulating solenoid, TCM or transmission assembly was replaced, perform the Q77 Transmission Control Solenoid Valve Characterization Programming (8L45) .
- Ignition ON, clear the DTCs with a scan tool.
- Ignition OFF, and all vehicle systems OFF. It may take up to 2 minutes for all vehicle control modules to power down.
- Engine running, transmission in drive position with brake applied. Perform the service fast learn procedure with a scan tool. Follow the instructions on the scan tool.
- Ignition OFF for 2 minutes.
If the transmission fluid temperature is not between 75°C (167°F) and 85°C (185°F) the scan tool will not allow you to perform the service fast learn procedure.