WORKHORSE CUSTOM CHASSIS
Service Manual
2007 W Series
SECTION
7.2
PAGE
278
Automatic Transmission – Allison
2007 W Series Chassis
© 2006 Workhorse Custom Chassis — All Rights Reserved
WSM082106
– A chafed wire
– A broken wire inside the insulation
• When diagnosing for an intermittent short or open,
massage the wiring harness while watching the test
equipment for a change.
• You may have to drive the vehicle in order to experience
a condition.
• When DTC P0751 and P0843 are set in combination,
this may indicate an open circuit condition is present at
the pressure switch circuit or the shift valve 1 is stuck in
the destroked position.
• This DTC may indicate that SS1 is mechanically
defective.
• This DTC can be caused by a loss of prime.
Test Description
The numbers below refer to the step numbers on the
diagnostic table.
5. This step tests the TCM response function.
6. This step tests the transmission wiring harness
integrity.
7. This step tests and evaluates the internal wiring
harness.
8. This step tests the PSM for a failed condition.
DTC P0843
Step
Action
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
