WORKHORSE CUSTOM CHASSIS
Service Manual
Automatic Transmission – Allison
2007 W Series
© 2006 Workhorse Custom Chassis — All Rights Reserved
SECTION
7.2
PAGE
223
2007 W Series Chassis
WSM082106
NEUTRAL.
• When in a forward range and the shift is in process, the
transmission will return to a previous range, except for 1-
2 shifts and 2-1 shifts where the shifts will be completed.
• When in NEUTRAL or REVERSE, the transmission will
fail to NEUTRAL.
• While diagnostic response is active, the shift selector
is moved from a forward range to NEUTRAL or from a
forward range to REVERSE, the transmission will shift to
NEUTRAL.
• DTC P0751 is stored in TCM history.
• The TCM freezes shift adapts.
• The TCM inhibits torque converter clutch (TCC)
engagement.
Conditions for Clearing the DTC
A scan tool can clear the code from TCM history. The
TCM automatically clears the DTC from TCM history if
the vehicle completes 40 warm-up cycles without failure.
Diagnostic Aids
• Inspect the wiring for poor electrical connections at the
TCM. Inspect for the following conditions:
– A bent terminal
– A backed-out terminal
– A damaged terminal
– Poor terminal tension
– 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.
• This DTC may indicate that SS1 is mechanically
defective or the shift valve is stuck in the destroked state.
• 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 is stuck in
the destroked position.
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.
