CHASSIS INFORMATION - 10
200
CAY M A N 2 0 0 7
Check Trans Indicator
The electronic control system of the
transmission is programmed to inform the
operator of a problem with the transmission
system and reacts automatically to protect the
operator, motorhome and transmission. When
the Electronic Control Unit (ECU) detects a DO
NOT SHIFT (DNS) condition the ECU restricts
shifting, turns on the CHECK TRANS light in
the instrument panel and registers a fault code.
NOTE:
For some problems, fault codes may be
registered without the ECU activating
the CHECK TRANS light. An Allison
Transmission authorized service outlet
should be consulted whenever there is a
transmission related concern. They have
the equipment to check diagnostic codes
and correct problems which may arise.
Each time the engine is started the CHECK
TRANS icon will light, then turn off after a
few seconds. This momentary lighting is to
indicate that the status light circuit is working
properly. If the CHECK TRANS light does not
illuminate during start up, or if the light remains
on after start up, the transmission system should
be checked immediately.
Continued illumination of the CHECK
TRANS light during vehicle operation (other
than start up) indicates that the ECU has
signaled a diagnostic code. Illumination of the
CHECK TRANS light is accompanied by a
ashing display from the shift selector. The shift
selector display will show actual range attained
and the transmission will not respond to shift
selector requests.
Indications from the shift selector are provided
to inform the operator that the transmission is
not performing as designed and is operating at
reduced capabilities. Before turning the ignition
off, the transmission may be operated for a short
time in the selected range in order to “limp
home” for service assistance. Service should be
performed immediately in order to minimize
potential damage to the transmission.
When the Check Trans icon illuminates the
keypad will not respond to command and 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. Locate a safe secure place to
park the motorhome. If the engine is shut off,
then engaged after a Check Trans indication,
the transmission remains in Neutral until the
fault causing the Check Trans light has been
corrected.
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.
Hold the Mode button for ten seconds to
clear both inactive and active codes.
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