WORKHORSE CUSTOM CHASSIS
Service Manual
2007 W Series
SECTION
7.2
PAGE
450
Automatic Transmission – Allison
2007 W Series Chassis
© 2006 Workhorse Custom Chassis — All Rights Reserved
WSM082106
to shift the transmission and observe the integrity of
each clutch/range in the transmission.
Attach the transmission pressure gage as described
in the Line Pressure Check Procedure. Refer to Line
Pressure Check Procedure . Apply the parking brake.
Hold the service brakes with your left foot and move
the gear selector to DRIVE. Increase engine speed to
1,400 RPM with your right foot. With soft keys, select
UPSHIFT and shift the transmission from FIRST gear
to SIXTH gear while observing turbine speed. Turbine
speed should increase momentarily and then drop to 0
RPM when each gear is attained. Line pressure should
drop momentarily, then gain pressure again when each
gear is attained.
Maintain 1,400 RPM and select the DOWNSHIFT
soft key. Downshift the transmission from SIXTH gear
sequentially to FIRST gear while observing turbine
speed. Turbine speed should increase momentarily and
then drop to 0 RPM when each gear is attained.
To further investigate a suspected leak in a clutch circuit,
the clutch test should be repeated, keeping the engine
at idle speed. While performing the clutch test at 600
RPM, main pressure should drop momentarily, then
gain pressure again when each gear range is attained.
If main pressure remains low, suspect damaged seal
in that range. If low pressure is in FIRST range only,
suspect Low and Reverse piston seal damage.
FASTLEARN PROCEDURE
Overview
In general, FastLearn 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, FastLearn translates it to the adaptive data
cells, which the TCM uses for clutch control during range
shifts. FastLearn is used at GM assembly plants, and
allows the vehicle to be driven out of the assembly plant
in a near-fully-adapted state to minimize any customer
shift concerns. The scan tool version of FastLearn
is intended to provide the same benefi t following
transmission repair or replacement at GM Dealerships.
FastLearn 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 the pressure control solenoids
• TCM replacement
• TCM software/calibration update
• Any service in response to a shift quality concern
The scan tool is used to initiate FastLearn by selecting
the following commands:
• F3: Special Functions
• F1: Transmission Output Controls
• FastLearn
