Peterbilt 220, Operator'S Manual

Page: 94 / 136

shift schedule in use. The MONITOR
digital display shows the lowest available
forward range.
Limited transmission operation can be
expected if the selector display shows
these conditions:
• All digital display segments are
illuminated during initialization. If
after 10 seconds communication is
not established with the TCM
(Transmission Control Module)
both digital displays show "cat
eyes".
• When the display shows a "cat
eyes", a selector-related fault code
has been logged.
• When the SELECT display shows
R (Reverse), or D has been
requested and the display is
flashing the selected range, the
selected range has not been
attained due to an inhibit function.
An inhibited range, shown by a flashing
display, does not indicate that a Diagnostic
Trouble Code (DTC) has set. An inhibit
means there is a vehicle or engine
condition that won't allow range selection
or a direction change such as
• Too high idle speed in N (Neutral)
to allow R or D,
• Too high a throttle signal in N to
allow R or D,
• Too high of an output speed in N to
allow R, or
• An active vehicle function or I/O
function is operating which inhibits
range attainment.
The transmission will not shift into range
from N if a transmission fault warning is
active. If a transmission fault warning is
active move vehicle to a safe location
before turning off the engine. Conditions
which illuminate a transmission fault
warning will disable the shift selector and
the MONITOR digit will show the actual
range attained instead of range selected.
Once D (Drive) is attained, the
transmission will shift into the lowest
forward range programmed for the D
position, usually the first-range.
To display stored codes, do the following:
• Select N and apply the parking
brakes.
• Simultaneously press the Up Arrow
and Down Arrow buttons once to
access oil level information (if an
OLS is installed).
• Simultaneously press the Up Arrow
and Down Arrow buttons
• Press the Mode button to display
the next code. Repeat for code
positions d3 through d5.
• Press N to exit the diagnostic code
mode.
Neutral Position
No gears are activated when the N button
is selected. The vehicle is not locked in this
position and can therefore roll.
Use the parking brake to lock the vehicle.
Automatic Forward Drive
If the D button is selected, the vehicle will
immediately begin to move (if the brake
system is pressurized and the vehicle is
not on the parking brake). It is therefore
advisable to depress the brake pedal
before selecting D. If in Drive the gearbox
will automatically shift up and down in all
forward gears. In the various drive
selections the gearbox shifts up to the
selected gear. These gears are used to
DRIVING - Allison Automatic Gearbox
92 Y53-6078-1B1 (12/18/18)
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