WORKHORSE CUSTOM CHASSIS
Service Manual
2007 W Series
SECTION
7.2
PAGE
106
Automatic Transmission – Allison
2007 W Series Chassis
© 2006 Workhorse Custom Chassis — All Rights Reserved
WSM082106
DTC P0218
Circuit Description
The fl ow of transmission fl uid starts in the transmission
pan. The transmission fl uid is then drawn through
the fi lter and the transmission case into the oil pump
assembly. The oil pump pressurizes the fl uid into
main pressure, that is regulated at the main pressure
regulator valve. From this point, fl uid is directed to
the torque converter clutch (TCC) solenoid and to the
control main regulator valve and control main relief
valve, into the control main fi lter assembly and on to all
solenoids for use as control pressure. Hot fl uid leaving
the torque converter is routed through the converter
fl ow valve, to cooler lines, and into the cooler assembly,
located in the radiator. The vehicle may be equipped
with an auxiliary oil cooler. The cooled fl uid is returned
to the transmission through the return cooler line and to
the transmission lube circuit. The automatic transmission
fl uid temperature (TFT) sensor, which is part of the
pressure switch manifold (PSM) assembly, is mounted to
the valve body.
If the transmission control module (TCM) detects a high
TFT for an extended period of time, then DTC P0218
sets.
DTC P0218 is a type C DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
• DTC P0218 Transmission Condition Overtemperature
Conditions for Running the DTC
• DTCs P0711, P0712, P0713 are not active.
• 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 for greater than 5
seconds.
Conditions for Setting the DTC
DTC P0218 sets when the TCM detects a transmission
sump temperature greater than 126°C (252°F) for 10
seconds.
Action Taken When the DTC Sets
• The TCM does not illuminate the malfunction indicator
lamp (MIL).
• The TCM freezes shift adapts from being updated.
• The TCM records the operating conditions when the
Conditions for Setting the DTC are met. The TCM stores
this information as Failure Records.
• The TCM stores DTC P0218 in TCM history.
• The TCM inhibits TCC engagement.
Conditions for Clearing the DTC
• A scan tool can clear the code from the TCM history. The
TCM automatically clears the DTC from TCM history if
the vehicle completes 40 warm-up cycles without failure.
• The TCM cancels the DTC default actions when the
condition no longer exists and the DTC passes the test.
