WORKHORSE CUSTOM CHASSIS
Service Manual
Automatic Transmission – Allison
2007 W Series
© 2006 Workhorse Custom Chassis — All Rights Reserved
SECTION
7.2
PAGE
237
2007 W Series Chassis
WSM082106
DTC P0757
Circuit Description
The pressure switch manifold (PSM) is a multiple-switch
assembly made up of 3 normally open (N/O) and 1
normally closed (N/C) pressure switches. The pressure
switch 2 (PS2) monitors shift solenoid valve 2 (SS2)
positioning and relays it to the transmission control
module (TCM). When PS2 is in the open state, SS2
should be in the destroked position.
DTC P0757 is a type A DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
• DTC P0757 Shift Solenoid (SS) 2 Valve Performance -
Stuck On
Conditions for Running the DTC
• The components are powered and ignition voltage is
greater than 9.0 volts and less than 18 volts.
• Engine speed is greater than 200 RPM and less than
7,500 RPM for 5 seconds.
• SS2 is commanded to the OFF, destroked, position.
Conditions for Setting the DTC
DTC P0757 sets when SS2 is commanded OFF and PS2 status
remains ON for 2-16 seconds, depending on fl uid temperature.
Action Taken When the DTC Sets
• The TCM illuminates the malfunction indicator lamp
(MIL).
• When in a forward range and shifting is completed, the
transmission will fail to another forward range, unless
the transmission is compromised by overspeeding or
direction change, then the transmission will shift to
NEUTRAL.
• When in a forward range and the shift is in process, the
transmission will return to a previous range, except for
1-2 shifts and 2-1 shifts which will be completed.
• When in NEUTRAL or REVERSE, the transmission will
fail to NEUTRAL.
• While diagnostic response is active, the shift selector
is moved from a forward range to NEUTRAL or from a
forward range to REVERSE, the transmission will shift to
NEUTRAL.
• DTC P0757 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
• Inspect the wiring for poor electrical connections at the
TCM. Inspect for the following conditions:
– A bent terminal
– A backed-out terminal
– A damaged terminal
