WORKHORSE CUSTOM CHASSIS
Service Manual
2007 W Series
SECTION
7.2
PAGE
190
Automatic Transmission – Allison
2007 W Series Chassis
© 2006 Workhorse Custom Chassis — All Rights Reserved
WSM082106
– 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.
Test Description
The numbers below refer to the step numbers on the
diagnostic table.
2. This step tests ignition voltage.
3. This step tests the wiring at the TCM.
4. This step tests engine speed sensor resistance.
