Appendix C – Allison Diagnostic Troubleshooting Codes
188
DIAGNOSTIC TROUBLESHOOTING CODES (DTC) — ALLISON 4
TH
GENERATION
CONTROLS
DIAGNOSTIC TROUBLESHOOTING CODES (DTC) OVERVIEW
Diagnostic codes (DTC) are numerical indications relating to a malfunction in transmission operation.
These codes are logged in a list in the TCM memory with the most severe or most recent code listed first.
A maximum of five codes (numbered d1 to d5) may be listed in memory at one time. As codes are added,
the oldest inactive code is dropped from the list. If all codes are active, the code with the lowest priority
that is not included on the severity list is dropped from the list.
Diagnostic codes (DTC) and code information may be accessed through the pushbutton shift selector or
using an Allison DOC™ diagnostic tool.
The TCM separately stores the active and inactive codes. An active code is any code that is current in the
TCM decision-making process. Inactive codes are codes that are retained in the TCM memory and will
not necessary affect the TCM decision-making process. Inactive codes are useful in determining if a
problem is:
•
Isolated
;
•
Intermittent
;
•
Result from a previous malfunction.
The TCM may automatically delete a code from memory if it has not recurred. If the
condition which generated the code is active, the LED indicator on the selector will be
illuminated simultaneously with the display of the code. If the condition which generated
the code no longer exists, the LED is not illuminated and the code is maintained only as a
historical record of the prior condition. An illuminated MODE INDICATOR (LED) during
normal operation signifies secondary shift mode operation.
DIAGNOSTIC CODES – ALLISON 4
TH
GENERATION CONTROLS
When the diagnostic mode is entered, the first code (position d1) is displayed as follows:
Exemple: Code P0722
Displayed as:
d1
…
P
…
07
…
22
The code list position is the first item displayed, followed by the DTC. Each item is displayed for about
one second. The display cycles continuously until the next code list position is accessed by pressing the
MODE
button. The following example shows how DTC P0722 is displayed on the pushbutton shift
selector.
d 1
P
0 7
SELECT
2 2
MONITOR
•
d1 (code list position) – The position which a
code occupies in the list. Positions are
displayed as « d1 » through « d5 » (code list
position 1 through code list position 5).
•
P0722 (DTC) – The diagnostic troubleshooting
code number referring to the general condition
or area of fault detected by the TCM.
Summary of Contents for X3-45 2011
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