freightliner M2 Plus 2023 Manual page 186

Automated and Automatic Transmissions
IMPORTANT: Maintain the proper fluid level at
all times. If the fluid level is too low, the
converter and clutch do not receive an adequate
supply of fluid. If the level is too high, the
transmission may shift erratically or overheat.
To access the oil level display mode, park the vehicle
on a level surface, shift to N (neutral), apply the
parking brake, and idle the engine. Then
simultaneously press both the up and down arrows
once. The oil level will display at the end of a two-
minute countdown.
Diagnostic Codes
Diagnostic codes are numerical indications relating to
a malfunction in transmission operation. These codes
are logged in the TCM/ECU memory. The most
severe or most recent code is listed first. A maximum
of five codes (numbered d1-d5) may be listed in
memory at one time. If the mode indicator LED is
illuminated, the displayed code is active. If it is not
illuminated, the displayed code is not active.
NOTE: During normal operation, an illuminated
mode indicator LED signifies the specialized
mode operation is in use.
To enter diagnostics mode, first park the vehicle and
apply the parking brake. Then simultaneously press
both the up and down arrows twice.
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