Allison Transmission Emergency Vehicle Series Operator's Manual page 25

Digital Display. During normal operation, if D (Drive) is selected, the digital
display shows the highest forward range attainable for the shift schedule in use.
Abnormal operation is indicated by the WTEC III digital display as follows:
• When all segments of the digital display are illuminated for more than
12 seconds, the ECU did not complete initialization.
• When the digital display is blank, there is no power to the selector.
• When the display shows a "
been logged.
• Conditions which illuminate the CHECK TRANS light disable the shift
selector and the digital display displays the range actually attained. For a
detailed explanation, refer to the CHECK TRANS LIGHT paragraph in the
DRIVING TIPS section.
Abnormal operation is indicated by the Allison 4
display as follows:
• When all segments of the digital display are illuminated, the shift selector
did not complete initialization.
• When both digital displays remain blank for 10 seconds after initialization
and then show a "
with the TCM or has experienced an internal fault.
• When the display shows a "
been logged.
• Conditions which illuminate the CHECK TRANS light disable the shift
selector. The SELECT digit is blank and the MONITOR digit displays the
range actually attained. For a detailed explanation, refer to the CHECK
TRANS LIGHT paragraph in the DRIVING TIPS section.
The transmission will not shift into range if a CHECK TRANS code is active.
When the display shows R or D has been requested and the display is flashing,
the requested range has not been achieved due to an inhibit function.
Some inhibit functions are vehicle-related and do not result in diagnostic codes.
Some examples are mentioned in the Range Selection tables at the end of this
Section.
Check for active codes if no other inhibit function has been located. Once
D (Drive) is attained, the transmission will shift into the lowest range programmed
for the D (Drive) position, usually first-range.
Display Mode/Diagnostic Button. The DISPLAY MODE/DIAGNOSTIC button
allows access to optional fluid level check information and diagnostic code
information. Press the DISPLAY MODE/DIAGNOSTIC button once to obtain
transmission fluid level information and a second time to obtain diagnostic code
information.
\
/ " (cateye), a selector-related fault code has
\
\
/ " (cateye), the shift selector is unable to communicate
\
\
/ " (cateye), a selector-related fault code has
\
24
th
Generation Controls digital