PREVOST X3-45 2016, Maintenance Manual

Page: 195 / 459

Section 07: TRANSMISSION
PA1593
15
CAUTION
Place the battery master switch to the ‘’OFF’’
position.
8.2 DIAGNOSTIC TROUBLESHOOTING
CODES (DTC) — ALLISON 4TH
GENERATION CONTROLS
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 MODE
INDICATOR (LED) is not
illuminated, the displayed code is
not active. An illuminated MODE
INDICATOR (LED) during normal
operation signifies secondary shift
mode operation.
8.3 DIAGNOSTIC CODES – ALLISON 4
TH
GENERATION CONTROLS
When the diagnostic mode is entered, the first
code (position d1) is displayed as follows:
Example: 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.
SELECT
d 1
MONITOR
P
0 7
2 2

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.
8.4 DIAGNOSTIC CODE DISPLAY AND
CLEARING PROCEDURE – ALLISON
4
TH
GENERATION CONTROLS
Diagnostic codes can be read and cleared by
two methods:
o
Using an Allison DOC™ diagnostic tool. For
specific instructions on how to use an Allison
DOC™ diagnostic tool, refer to the User
Guide.
o
Using the pushbutton shift selector.