WORKHORSE CUSTOM CHASSIS
Service Manual
2007 W Series
SECTION
7.2
PAGE
196
Automatic Transmission – Allison
2007 W Series Chassis
© 2006 Workhorse Custom Chassis — All Rights Reserved
WSM082106
DTC P0729
Step
Action
Value
Yes
No
11
With the scan tool, observe the stored information, capture info, and DTC
Info.
Does the scan tool display any DTCs that you have not diagnosed?
—
Go to Diagnostic
Trouble Code (DTC)
List - Vehicle
System OK
DTC P0731
Circuit Description
The transmission control module (TCM) uses input
from the turbine speed sensor and the output speed
sensor (OSS) to determine gear ratios. The TCM then
compares the known gear ratio to the calculated gear
ratio for the current range.
DTC P0731 is a type A DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
• DTC P0731 Incorrect 1st Gear Ratio
Conditions for Running the DTC
• DTCs P0716, P0717, P0721, P0722, P0726, P0727,
P0875, and P0876 are not active.
• The components are powered and ignition voltage is
greater than 9.0 volts and less than 18 volts.
• Output speed exceeds 200 RPM.
• 1st range is selected and attained.
Conditions for Setting the DTC
DTC P0731 sets when the calculated 1st range ratio, steady
state, differs from the known 1st range ratio.
Action Taken When the DTC Sets
• The TCM illuminates the malfunction indicator lamp
(MIL).
• The transmission defaults to 2nd or 5th range while
diagnostic response is active.
• If the shift selector is moved to NEUTRAL, the
transmission will shift to NEUTRAL.
• If the shift selector is moved to REVERSE, the
transmission will either lock in NEUTRAL or shift to
REVERSE, unless the transmission is compromised by
overspeeding or direction change, then the transmission
will lock in NEUTRAL.
• DTC P0731 is stored in TCM history.
• The TCM freezes shift adapts.
• The TCM inhibits torque converter clutch (TCC)
engagement.
Conditions for Clearing the DTC
A scan tool can clear the code from TCM history. The
TCM automatically clears the DTC from TCM history if
the vehicle completes 40 warm-up cycles without failure.
Diagnostic Aids
• Incorrect ratio codes typically indicate mechanical