WORKHORSE CUSTOM CHASSIS
Service Manual
Automatic Transmission – Allison
2007 W Series
© 2006 Workhorse Custom Chassis — All Rights Reserved
SECTION
7.2
PAGE
61
2007 W Series Chassis
WSM082106
position is communicated to the TCM so that certain
vehicle control functions can be coordinated with the
position of the shift controls. The IMS has redundant
circuitry to alert the TCM in the event of a single wire
or switch failure. The neutral signal output of the IMS is
typically used as confi rmation that the transmission is
in NEUTRAL before the engine starter is engaged. The
IMS is interfaced to the starter circuit.
The operator chooses the transmission range by moving
the selector lever to the appropriate gate position. When
properly adjusted, the shifter gates prevent inadvertent
shifting between ranges, and corresponds to the internal
transmission detent positions. A positive detent is
provided in the transmission in order to maintain the
selector shaft in the selected position.
The TCM shift calibration determines the available
forward ranges for each selector position. Although
specifi c installations vary, typical selector positions for
the 1000 Series include the following:
P - PARK: The parking pawl is engaged. The
transmission is in NEUTRAL.
R - REVERSE: REVERSE is selected in order to move
the vehicle backward.
N - NEUTRAL: NEUTRAL may be used when starting
the engine and for stationary operations. The TCM
disables the starter switch if a range other than
NEUTRAL or PARK is selected before starting the
vehicle.
D - DRIVE: DRIVE is the highest forward range used for
normal driving. The transmission shifts to fi rst range for
starting, then automatically upshifts through the ranges,
as operating conditions permit, until the highest range is
attained.
M - Manual: Manual selection of ranges is provided
by moving the selector to the M - MANUAL position.
A driver shift request switch has been added to the
column shift lever. The driver information center (DIC)
then shows the 6 available ranges with the current range
bracketed. The bracketed range is the highest attainable
range with all gears below accessible, for example,
when 4th range is selected, ranges 1st through 4th are
available. By using the +/- buttons on the gear select
lever, the driver can select the range of gears desired for
their current driving conditions.
1 - Manual LOW: Manual LOW provides fi rst gear
operation only.
Internal Components
Several components of the 1000 Series electrical control
system are located within the transmission as part of the
main control valve body. These components include 3
types of solenoids for controlling the hydraulic action of
the valves. They include the PSM and an internal wiring
harness that links the internal components with the
TCM.
