WORKHORSE CUSTOM CHASSIS
Service Manual
2007 W Series
SECTION
7.2
PAGE
54
Automatic Transmission – Allison
2007 W Series Chassis
© 2006 Workhorse Custom Chassis — All Rights Reserved
WSM082106
Externally Generated Electronic Interference (Speed
Sensor Signals)
Use the following procedures in order to determine if
speed sensor signals, generated by a source external to
the transmission or wiring harness, are present:
1. Turn the ignition ON.
2. Keep the engine OFF.
3. If the transmission control module (TCM) is ON, install
the scan tool.
IMPORTANT:
If false speed signals were present at the previous
If false speed signals were present at the previous
shutdown, the TCM might still be ON, even though
shutdown, the TCM might still be ON, even though
the ignition is OFF. The scan tool is powered by igni-
the ignition is OFF. The scan tool is powered by igni-
tion power. The ignition must be ON in order to use the
tion power. The ignition must be ON in order to use the
scan tool to read the speed signals.
scan tool to read the speed signals.
4. Read the speed sensor signals.
5. If a speed sensor signal is something other than one
(1), there is a short to another circuit that is carrying an
AC or pulse width modulated (PWM) signal.
6. Measure the resistance of the sensor.
7. Inspect for shorts to other circuits within the harness or
transmission connector.
8. Inspect to ensure there is no conductive material
inside the connector.
9. Inspect to ensure the speed sensor circuit wires are a
twisted pair.
10. Inspect to ensure a properly grounded drain wire.
11. Inspect for the presence of a strong external AC signal.
12. Repair or replace parts as required.
TRANSMISSION GENERAL DESCRIPTION
Allison 1000 Series transmissions are torque converter
driven, fully automatic, transmission systems. The 1000
Series transmissions have 6 forward speeds, NEUTRAL,
and REVERSE. The fi fth and sixth range has overdrive
gear ratio. The 1000 Series incorporates a variety of
standard and optional design features. These design
features include the following:
• Direct mount to engine block
• Flexplate drive
• Torque converter with a torque converter clutch (TCC)
and integral vibration damper
• 3 constant-mesh planetary gear sets with helical gears
• 5 multiple disk clutches - 2 rotating and 3 stationary
• Common hydraulic system for all transmission functions
• 2 transmission fl uid fi ltration systems
• Electrohydraulic control valve assembly
• Electronically controlled automatic gear selection and
clutch apply
• Fill tube/dipstick provision on both sides of transmission
• Parking pawl
• Power takeoff (PTO) provision on both sides of
transmission
