WORKHORSE CUSTOM CHASSIS
Service Manual
Automatic Transmission – Allison
2007 W Series
© 2006 Workhorse Custom Chassis — All Rights Reserved
SECTION
7.2
PAGE
439
2007 W Series Chassis
WSM082106
DTC P2771
Step
Action
Yes
No
8
Replace the transfer case control module. Refer to Transfer Case Shift Control Module
Replacement .
Did you complete the replacement?
Go to Step 16
—
9
Using the transfer case selector, select 4HI followed by 4LO.
Does the scan tool indicate 4WD low status as NO for both selector positions?
Go to Step 10
Go to Step 15
10
1. Remove the connector at the transfer case switch.
2. Ground the 4WD low signal circuit to a known ground.
Does the scan tool indicate 4WD low status as NO?
Go to Step 11
Go to Step 13
11
Inspect the short to ground in the brake switch signal circuit. Refer to Circuit Testing
and Wiring Repairs .
Did you find a condition?
Go to Step 12
Go to Step 15
12
Repair the open condition in the 4WD low signal circuit. Refer to Circuit Testing and
Wiring Repairs .
Did you complete the repair?
Go to Step 16
—
13
Inspect the transfer case switch for an open condition.
Did you find an open condition?
Go to Step 14
Go to Step 15
14
Replace the transfer case switch. Refer to Transfer Case Shift Control Switch
Replacement .
Did you complete the replacement?
Go to Step 16
—
15
IMPORTANT:
In most cases, the TCM is not at fault. Investigate thoroughly before
In most cases, the TCM is not at fault. Investigate thoroughly before
replacing the TCM.
replacing the TCM.
Replace the TCM. Refer to Control Module References for replacement, setup, and
programming.
Did you complete the replacement?
Go to Step 16
—
