SECTION 10 — CHASSIS INFORMATION
228
CAMELOT 2007
NOTE
The transmission will not shift into gear
from Neutral if the engine RPM is at or
above 900. The display will flash “66”
indicating the engine RPM is excessive.
Select “N” and lower engine RPM.
Check Trans Indicator
The electronic control system of the
transmission is programmed to alert operator
of a problem with the transmission system, and
reacts automatically to protect the motorhome
and transmission from damage. Normally, the
Check Trans indicator on the speedometer LCD
will display when there is an error condition. The
indicator will go out after the engine has started.
The transmission system should be checked
immediately if the Check Trans indicator
displays. The Check Trans warning indicates
the ECU has detected a fault and recorded a
diagnostic code. The Check Trans warning is
accompanied by a ashing display from the shift
selector.
The shift selector display shows the actual
range attained and the transmission does not
respond to shift selector requests when the
ECU detects a Do Not Shift (DNS) condition.
Indications from the shift selector inform the
operator that the transmission is operating
at reduced capabilities. The transmission
generally will downshift to 4th gear. The torque
converter will not “lock-up” and engine speed
is automatically reduced. Direction changes
(i.e. forward to reverse) will not be allowed.
This allows time to nd a safe place to park the
motorhome to prevent transmission damage. If
the engine is shut off, then started after a Check
Trans indication, the transmission remains
in Neutral until the fault has been corrected.
Service should be performed immediately in
order to minimize potential damage to the
transmission.
NOTE
Contact an authorized Allison
Transmission service center whenever
a transmission related concern arises.
For some problems, fault codes
may be registered without the ECU
activating the Check Trans indicator. An
authorized Allison Transmission Service
center will have the equipment to check
diagnostic codes and correct problems
that may arise.
Diagnostic Codes:
The shift selector can be used to display
transmission malfunctions as numerical codes.
Each code is a two-digit main code and a
two-digit sub code. These codes will fall in
two classes: active and inactive. Active codes
are codes currently affecting the ECU process
and transmission operation. Inactive codes are
retained in memory but may not affect the ECU
process or transmission operation. A service
technician will activate Diagnostic mode or hook
an electronic display (Pro-Link) to the data plug
to retrieve diagnostic codes. A maximum of ve
codes, D1 to D5, may be listed at one time. The
highest priority code will be listed in D1. The
Mode button will enable selection of sequential
codes. Allison 4th Generation controls list each
code consisting of ve characters. The rst being
a letter followed by a four digit number string.
The most severe or recent code is listed in the
ECU memory rst with a maximum of ve
codes being d1 to d5 possibly listed at the same
time. When new codes are added, the oldest
inactive codes will be dropped.
To Display Diagnostic Codes:
Stop the motorhome at a safe location.
Apply the parking brake.
Simultaneously press the up and down
arrows once to enter oil level display
mode. Then press the up and down
arrows again to enter diagnostic mode.
The codes will display one digit at a
time or two characters at a time on 4th
Generation controls.
Press the mode button to scroll through
the codes.
Record all diagnostic codes that are
displayed. The codes then can be used by
an Allison Service Center for evaluation
and repair.
Inactive codes can be cleared by holding
the Mode button for approximately three
seconds. 4th Generation controls require
holding the Mode button for ten seconds
to clear both inactive and active codes.
Some codes are self-clearing while others will
require service or ignition on/off cycles to clear.
Periodic Inspections
The Allison MH Series requires very little
maintenance. Careful attention to the uid level,
electrical connections and hydraulic hoses is
very important.
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