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WORKHORSE CUSTOM CHASSIS
Service Manual
Automatic Transmission – Allison
2007 W Series
© 2006 Workhorse Custom Chassis — All Rights Reserved
SECTION
7.2
PAGE
409
2007 W Series Chassis
WSM082106
DTC P2724
Circuit Description
Pressure control solenoid 1 (PCS1) is used to control
on-coming, off-going, and holding pressure in any 1 of
5 clutches. This solenoid is referred to as a pressure
proportional to current (PPC) solenoid, since the
output hydraulic pressure supplied by this solenoid is
proportional to the controlled current command.
The transmission control module (TCM) uses
information from the turbine and output speed sensors to
detect if a clutch is slipping. The clutch being controlled
by PCS1 will vary depending on the shift that was being
completed.
DTC P2724 is a type A DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
• DTC P2724 Pressure Control Solenoid 1 (PCS1)
Controlled Clutch Stuck On
Conditions for Running the DTC
• DTCs P0716, P0717, P0721, P0722, 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 is greater than 200 RPM.
• Turbine speed is greater than 200 RPM.
Conditions for Setting the DTC
DTC P2724 sets when the TCM determines the off-going clutch
controlled by pressure control solenoid 3 (PCS3) remains
engaged during a forward range shift.
Action Taken When the DTC Sets
• The TCM illuminates the malfunction indicator lamp
(MIL).
• When failure occurs in a forward range, the transmission
will go to the previous range. If failure occurs in
NEUTRAL or REVERSE, the transmission will lock in
NEUTRAL 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 shift to REVERSE or NEUTRAL or in
some cases may lock in NEUTRAL.
• If the shift selector is returned to a forward range and
the transmission is compromised by overspeeding or
direction change, the transmission will shift to NEUTRAL.
• DTC P2724 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