Workhorse ALLISON 1000MH Service Manual page 396

WORKHORSE CUSTOM CHASSIS
Service Manual
DTC P1779
Step
Schematic Reference: Automatic Transmission Controls Schematics
1 Did you perform the 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 the Before clearing the DTC, use the scan tool in order to record the
Freeze Frame and Failure Records. The Clear Info function will Freeze Frame and Failure Records. The Clear Info function will
erase the data. erase the data.
3. Record the DTC Freeze Frame and Failure Records.
4. Turn the ignition OFF.
5. Disconnect the 80-way connector at the TCM.
6. Inspect the terminal 44 for a pulled back, unlocked, terminal or visible terminal
damage.
Did you find and correct a condition?
3 1. Disconnect the ECM.
2. Inspect the delivered torque signal circuit for a pulled back, unlocked, terminal
or visible terminal damage.
Did you find and correct a condition?
4 Test the unmanaged torque signal circuit between the TCM and ECM for an open or
short to ground. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct a condition?
5 Verify that the ECM has the proper model year software and calibration. This wiring
option is only used with the 8.1L gas engine.
Was the software and calibration current and proper for the engine?
6 Install the correct ECM calibration. Refer to Control Module References for replace-
ment, setup, and programming.
Is the calibration complete?
WSM082106
PAGE
SECTION
7.2 396
Action
© 2006 Workhorse Custom Chassis — All Rights Reserved
Automatic Transmission – Allison
Yes
Go to Step 2
Go to Step 8
Go to Step 8
Go to Step 8
Go to Step 7
Go to Step 8
2007 W Series Chassis
No
Go to Diagnostic
System Check - Vehicle
Go to Step 3
Go to Step 4
Go to Step 5
Go to Step 6
—
2007 W Series