Transmission Control Module (ALLISON): Overview

WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

In general, Fast Learn is a procedure for Allison 1000 Series transmissions in which a series of tests are run to allow the Transmission Control Module (TCM) to "learn" individual clutch characteristics. Once the clutch data is learned, Fast Learn translates it to the adaptive data cells, which the TCM uses for clutch control during range shifts. Fast Learn is used at GM assembly plants and allows the vehicle to be driven out of the assembly plant in a near-fully-adapted state so as to minimize any customer shift complaints. The scan tool version of Fast Learn is intended to provide the same benefit following transmission repair or replacement at GM Dealerships.

Fast Learn must be used when one of the following repairs have been made to the vehicle:

Transmission replacement or internal service/overhaul.
Valve body repair or replacement, including replacement of "A" or "B" solenoids.
Transmission control module replacement.
TCM software/calibration update.
Any service in response to a shift quality complaint.

The scan tool is used to initiate Fast Learn by selecting the following commands:

F3: Special Functions.
F1: Transmission Output Controls.
Fast Learn.

When performing Fast Learn, the following conditions must be met:

Block drive wheels.
Apply parking brake.
Apply service brake during Drive and Reverse mode.
0% throttle, engine at idle RPM.
Transmission sump temperature at 40-100°C (Reference temperature bar graph on scan tool screen).
If equipped, 4WD transfer case in 2WD.

If at any time during the procedure, required conditions are not met, Fast Learn may abort and the process will need to be re-started from the beginning.