Section 4
TROUBLESHOOTING CHARTS
TM 9-2320-363-20-1
C. START- FIRST CHART FOR DIAGNOSIS OF DDEC-II USING DDR (Cont’d.)
STEP/SEQUENCE
START-8 Check for Short
• Turn ignition off.
• Disconnect the vehicle harness
connector at the ECM.
• Read resistance between pins A
and M of the 12 pin, DDL
connector.
START-9 Check for +12
Volts at DDL
Connector
• Turn ignition on.
• Read voltage at the 12 pin DDL
connector, from pin H to pin A.
START-10 Check ECM
Connectors
• Disconnect the 6-way power
harness connector at the ECM.
• Check terminals at the ECM 6-way
power and vehicle harness
connectors (both the ECM and
harness side) for damage; bent,
corroded and unseated pins or
sockets.
RESULT
I
WHAT TO DO NEXT
The Diagnostic Request line
(Ckt #451) is shorted to ground
either ckt #150 or chassis
ground). Contact Direct Support.
Go to START-1O
There is a problem with either the
DDR or the data link lines. Go to
C7-4 (page 3-179). (For diagnosis
of DDEC-II without a DDR, go to
CEL-1 on page 3-131).
Either the switched +12 volt line
(ckt #439 or other appropriate
circuit) or the ground line is open
to the 12 pin, DDL connector.
Repair open. Then go to
START-30.
Replace ECM, page 4-192.
Then go to START-30.
Repair terminals/connectors.
Then go to START-30.
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