WORKHORSE CUSTOM CHASSIS
Service Manual
2007 W Series
SECTION
7.2
PAGE
120
Automatic Transmission – Allison
2007 W Series Chassis
© 2006 Workhorse Custom Chassis — All Rights Reserved
WSM082106
DTC P0602
Circuit Description
When the ignition is turned on and the transmission
control module (TCM) is powered up or when DTCs are
cleared, the TCM performs a self-test to determine if the
calibration is valid.
DTC P0602 is a type C DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
• DTC P0602 Transmission Control Module (TCM) Not
Programmed
Conditions for Running the DTC
• The components are powered and ignition voltage is
greater than 9.0 volts and less than 18 volts.
• This test will run before any TCM function.
Conditions for Setting the DTC
DTC P0602 sets if the TCM determines the present
calibration is invalid.
Action Taken When the DTC Sets
• The TCM does not illuminate the malfunction indicator
lamp (MIL).
• The transmission is limited to forward range, due to
presence of default calibration.
• The TCM returns to the boot program, and then waits to
be calibrated.
• The TCM inhibits torque converter clutch (TCC)
engagement.
Conditions for Clearing the DTC
The TCM must be calibrated.
Diagnostic Aids
DTC P0602 may set because of improper TCM
reprogramming.
