WORKHORSE CUSTOM CHASSIS
Service Manual
2007 W Series
SECTION
7.2
PAGE
174
Automatic Transmission – Allison
2007 W Series Chassis
© 2006 Workhorse Custom Chassis — All Rights Reserved
WSM082106
• 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.
• If the condition is intermittent, connect the scan tool and
select the speed sensor indicated by the code. If the
signal is erratic, investigate and eliminate the following:
– Intermittent wiring connection
– Excessive vibration, such as driveline or engine
torsionals
– Irregular sensor gap, such as a loose sensor, a loose
tone wheel or a damaged tone wheel
– Inspect that the speed sensor wiring consists of twisted
pairs at the rate of 12-16 twists per 300 mm (12 in).
These twists must extend the entire length of the
wiring harness to within at least 50 mm (2 in) of the
speed sensor connector.
