Allison Transmission Emergency Vehicle Series Operator's Manual page 28

PUSHBUTTON AND LEVER SHIFT SELECTORS
Description of Available Ranges (refer to Figure 11 and Figure 12)
WARNING: If you leave the vehicle and the engine is running,
the vehicle can move unexpectedly and you or others could be
injured. If you must leave the engine running, do not leave the
vehicle until you have completed all of the following
procedures:
WARNING: R (Reverse) may not be attained due to an active
inhibitor. Always apply the service brakes when selecting
R (Reverse) to prevent unexpected vehicle movement and
because a service brake inhibit may be present. When "R" is
flashing, it indicates the shift to R (Reverse) is inhibited. Check
for active diagnostic codes if R (Reverse) is not attained. See
DOWNSHIFT AND DIRECTION CHANGE INHIBITOR
FEATURE in the DRIVING TIPS section.
CAUTION: Do not idle in R (Reverse) for more than
five minutes. Extended idling in R (Reverse) can cause
transmission overheating and damage. Always select N (Neutral)
whenever time at idle exceeds five minutes.
NOTE: Visually check the digital display window whenever a
button is pushed or the lever is moved to be sure the range selected
is shown (i.e., if the N (Neutral) button is pressed, "N" should
appear in the digital display). A flashing display indicates the range
selected was not attained due to an active inhibit.
WITH DIGITAL DISPLAY
1. Put the transmission in N (Neutral).
2. Be sure the engine is at low idle (500–800 rpm).
3. Apply the parking brakes and emergency brake and make
sure they are properly engaged.
4. Chock the wheels and take any other steps necessary to
keep the vehicle from moving.
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