A Pac Brake wired to electronically controlled transmission will usually
provide converter lockup in gears 2 through 6, meaning brake will activate
automatically when throttle is released. Once on, brake will control existing
road speed and/or slow sufficiently so Allison Transmission will automatical-
ly downshift, if necessary, to calibration pre-select mode.
The Allison World transmission incorporates the World Transmission
Electronic Control (WTEC) system. The system is compromised of five
major components connected by a wiring harness: the electronic control unit
(ECU), engine throttle position sensor, three speed sensors, remote shift
selector (keypad) and the control module. The ECU will process information
received from the throttle position sensor, speed sensor, pressure switch and
shift selector to activate solenoids on the control module in the transmission.
The solenoids control oncoming and offgoing clutch pressure to provide
closed loop shift control. This is accomplished by matching RPM during a
shift to an established desired profile within the ECU.
The system is monitored within the first 30 seconds of each engine start.
This is referred to as “autodetect.” Autodetect searches for presence of data
inputs or transmission components. The autodetect enables the ECU func-
tional or diagnostic response to the items which are detected.
Another feature of the transmission is the ability to “learn” or “adapt.”
The electronic control system optimizes shift quality by using “Adaptive
Shifting.” A wide variety in shifting under varied conditions will be required
before optimizing the shift quality. Generally five typical shifts of a shift type
are needed for shift calibration.
The range selection is accomplished via the remote push button selector.
The selector is simplistic in appearance. The controls are R, N, D, arrow up,
arrow down, MODE buttons and a digital display window. Under normal
operations the “D” button is pressed and the digital display shows the highest
forward range attainable for the shift selection in use. The digital display
window will also indicate codes for abnormal conditions and can even be a
useful troubleshooting aid. When the ignition is turned ON the display
should be visible. This display indicates the presence of neutral start com-
mand. If this display indication is not visible there is no power to the selector
and may indicate electrical problems with the batteries.
• Digital display window enables information requested to be easily read.
• Select the Reverse gear by pressing “R”.
• Select NEUTRAL by pressing “N”. The area around the “N” button is a
raised ridge so the driver can orient his hand to the push buttons by
touch, without looking at the display.
• Select DRIVE range by pressing “D”. The highest forward gear will
appear on the SELECT display and the transmission will shift to the
starting gear.
Chassis Information
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WINDSOR
10•287
TRANSMISSION -
Shift Selector
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