WORKHORSE CUSTOM CHASSIS
Service Manual
Automatic Transmission – Allison
2007 W Series
© 2006 Workhorse Custom Chassis — All Rights Reserved
SECTION
7.2
PAGE
179
2007 W Series Chassis
WSM082106
DTC P0721
Step
Action
Value
Yes
No
Schematic Reference: Automatic Transmission Controls Schematics
1
Did you perform the Diagnostic System Check - Vehicle?
—
Go to Step 2
Go to Diagnostic
System Check
- Vehicle
2
1. Install the scan tool.
2. Turn ON the ignition, with the engine OFF.
IMPORTANT:
Before clearing the DTC, use the scan tool in order to record
Before clearing the DTC, use the scan tool in order to record
the Freeze Frame and Failure Records for reference. The Clear
the Freeze Frame and Failure Records for reference. The Clear
Info function will erase the data.
Info function will erase the data.
3. Record the DTC Freeze Frame and Failure Records.
4. Clear the DTC.
5. Using the scan tool, observe ignition voltage.
Is the voltage within the specified range?
9-18 V
Go to Step 3
Go to DTC
P0562 for low
voltage or DTC
P0563 for high
voltage
3
1. Turn the ignition OFF.
2. Disconnect the 80-way connector at the TCM.
3. Install the J 39700 breakout box, the J-47275 breakout box adapter and
the J 47275-1 magnetic overlay.
4. Using the DMM, measure the resistance between connector terminals 60
and 40.
Is the speed sensor resistance within the specified value?
2,600-3,160 ohms Go to Diagnostic
Aids
Go to Step 4
4
1. Disconnect the wiring harness from the output speed sensor.
2. Using the DMM and the J 35616 GM terminal test kit, measure the resis-
tance between the speed sensor terminals.
Is the speed sensor resistance within the specified value?
2,600-3,160 ohms Go to Step 5
Go to Step 6
5
Test the output speed sensor circuit between the TCM and output speed sensor
for an open or short to ground condition. Refer to Circuit Testing.
Did you find and correct the condition?
—
Go to Step 7
—
