WORKHORSE CUSTOM CHASSIS
Service Manual
Automatic Transmission – Allison
2007 W Series
© 2006 Workhorse Custom Chassis — All Rights Reserved
SECTION
7.2
PAGE
261
2007 W Series Chassis
WSM082106
diagnostic table.
3. This step tests signal voltage to the TCM.
4. This step tests supply voltage to the driver shift
request switch.
5. This step tests resistance of the driver shift request
switch.
DTC P0826
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
the Freeze Frame and Failure Records for reference. The
Clear Info function will erase the data.
Clear Info function will erase the data.
3. Record the DTC Freeze Frame and Failure Records.
4. Clear the DTC.
5. Using the scan tool, measure 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. Turn ON the ignition, with the engine OFF.
5. Using the DMM, measure voltage at terminal 56 and a known good
ground.
6. Operate the driver shift request switch in the TAP up and TAP down
position.
Is the voltage within the specified value?
2.5 V
Go to Diagnostic
Aids
Go to Step 4