Allison Transmission; Operation; Pushbutton Shift Selector; Primary And Secondary Shift Schedules - PREVOST H3-45 2023 Operator's Manual

74 - Controls and Instruments -

ALLISON TRANSMISSION

The transmission is fully automatic: Proper
ranges should be
according to driving speeds to improve vehicle
performance and control. The speed ratio of the
power converter changes automatically as
vehicle speed increases and direct-drive goes in
and out as necessary. The speed ratio is
modulated by vehicle speed and accelerator
pedal position. You will find the complete
transmission operation instructions and driving
tips in the Allison 5th & 6th Generation Operator's
Manual 3000_ 4000 Series available on the
Prevost Technical Publications site.

OPERATION

When a button is depressed on the transmission
control pad, the corresponding letter or number is
displayed indicating the transmission is ready to
operate in the selected range. If the transmission
control module (TCM) detects a serious problem
in the transmission, the CHECK telltale lights on
the dashboard.
FIGURE 54: ALLISON PUSHBUTTON SHIFT SELECTOR

PUSHBUTTON SHIFT SELECTOR

The pushbutton shift selector has the following
elements:
R: Press to select Reverse gear.
NOTE
The forward limit speed to activate the reverse
gear is 5 mph.
automatically selected
PA-1652 Operator's Manual H3-45 Coach
N: Press to select Neutral.
D: Press to select Drive. The highest forward range
available will appear in the digital display window
under SELECT. The transmission will start out in
the lowest available forward range, displayed under
MONITOR, and advance automatically to the
highest range.
Ç È : Press respectively the Ç (Upshift) or È
(Downshift) arrow button when in DRIVE to request
the next higher or lower range. One press changes
gears by one range. If the button is held down, the
selection will scroll up or down until the button is
released or until the highest or lowest possible
range is selected. Protection mechanisms inhibit
selecting ranges that are not appropriate for the
current speed or which may damage driveline
components.
MODE: Pressing the MODE button allows the driver
to activate the secondary shift schedule that has
been programed into the TCM unit.
PRIMARY AND SECONDARY SHIFT
SCHEDULES
The primary shift schedule is the default mode at
starting of the engine and is typically specified to
accommodate normal vehicle operation. The
transmission controller automatically selects
between ECONOMY and PERFORMANCE shift
strategy, based on the vehicle actual load and the
grade on which the vehicle is operating. This is
called Load Based Shift Scheduling (LBSS). This
can produce improved overall vehicle fuel
economy while still enabling high productivity
when the vehicle is loaded.
In the secondary shift schedule, only the
ECONOMY shift strategy is available. No
switching is done between shift strategies. The
secondary shift mode is available only if selected
by the driver, using the MODE button. When the
secondary mode is activated, "MODE" illuminates
on the display.
NOTE
When the diagnostic display mode has been
entered, the MODE button is used to view and
toggle through diagnostic code information.
Refer to appendix C for more details about
diagnostic code display procedure and fluid
level check using the pushbutton shift selector.