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TM 9-2320-360-20-1
Section IV. TROUBLESHOOTING
2-13. INTRODUCTION TO LOGIC TREE TROUBLESHOOTING
a.
Page Layout. The troubleshooting is divided into symptoms peculiar to a vehicle system or component (for
example, air system or fifth wheel). This manual cannot list all malfunctions that may occur, nor all tests, Inspections, or
corrective actions. If a malfunction is not listed or is not corrected by listed corrective actions, notify supervisor.
First, determine the symptom or condition that indicates a problem or failure. Refer to Table 2-5, Engine Electronic
Controls (DDEC) Troubleshooting or Table 2-7, Vehicle Troubleshooting following this introduction arranged by major
vehicle system.
Go to the referenced page to begin troubleshooting. Open the manual flat so that both the right and left hand pages are
displayed before you. The information on all facing pages is important.
All diagnostic logic and flowcharts are on the left hand page, with supporting information, warnings, cautions, notes, and
test instructions on the right. (See figure on next page.) Pages are set up so you do not need any more than the
necessary information, notes, warnings and cautions about a particular question. The experienced technician can
generally read just left hand pages and refer to information on the right page when needed. All critical information for
decisions is on the left page. Do the tests and inspections in the order listed, and try to return the vehicle or component to
operation after each test, inspection, and corrective action has been performed.
b.
How To Begin Troubleshooting
(1)
Identify the symptom or fault. Select the applicable symptom (grouped by systems). Follow Vehicle
Troubleshooting BEFORE going to DDEC Troubleshooting.
(2)
Follow the diagnostic procedure. Answer question no 1. on the left hand page and follow the YES or NO
path to either the remedy or the next question. Helpful information about the problem is also on the left
page Look on the right page for additional specific instructions and help.
(3)
Observe warnings, cautions, and notes. WARNING is the symbol for a warning statement. If you see this
block above a question on the left page, look on the right page for the text of the message. The WARNING
message on the right page will also have the symbol above it. CAUTION is the symbol for a caution
statement. If you see this block above a question on the left page, look on the right hand page for the text
of the message. The CAUTION message on the right hand page will also have the symbol above it
Examples:
WARNING
The ENGINE switch should always be OFF before the harness connectors are
disconnected or reconnected. Failure to comply may result in electrical shock.
CAUTION
When disconnecting harness connectors, apply pulling force to the connectors
themselves and not the wires extending from them Failure to comply will damage
wire.
NOTE
After harness connectors are reconnected to the DDEC system, the computer
diagnostics should be ignored and cleared.
c.
Measurements Required for Troubleshooting
(1)
Resistance Measurements
(a)
Connect the red test lead to the volt-ohm input connector and black lead to the Common (COM) input
connector on the meter.
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