DEF SCR SYSTEM (DCU)
5–81
CHECKLIST: P068A
DTC: P068A
Main relay
Inspection Procedure
Step
Action
Description
Judgement
Check
(Yes/No)
Yes
No
1
Check the
DTC detected
(DCU)
Check if any DTC other than
P068A (for example, P0562) has
been detected in [DTC].
NOTICE
If the battery switch is turned
OFF or a battery terminal is dis-
connected during the DCU
shutdown process, Diagnostic
Code P068A may be detected.
DTC other
than P068A
(for example,
P0562) has
been detected:
Go to YES.
No DTC has
been detected:
Go to NO.
Go to diagno-
sis procedure
of a related
DTC.
Go to step 2.
2
Inspect the
DCU power
supply circuit
Connect the signal check
harness to measure the voltage
between the terminals of the DCU
53P connector (Engine sub har-
ness-side) and the battery minus
(BAT-).
<Tester connections>
DCU 53P connector (Engine sub
harness side)-
+B1
–
BAT-
+B2
–
BAT-
+B3
–
BAT-
+B4
–
BAT-
<Standard values>
9 V
–
16 V
The measure-
ments meet
the standard
value: Go to
YES.
The measure-
ments do not
meet the stan-
dard value: Go
to NO.
Go to step 3.
Repair or
replace the
battery power
supplying cir-
cuit (harness,
fuse etc).
Perform "After-
inspection
work" of
INFORMA-
TION section.
3
Inspect the
DCU harness
Using the electrical tester, mea-
sure the resistance between the
terminals from the DCU 53P vehi-
cle side connector to the chassis-
side connector of the cab main
harness connector to chassis
front harness connector.
<Tester connections>
DCU 53P connector (Vehicle
side) to chassis side connector of
the cab main harness
+B1
–
#GT
+B2
–
#GT
+B3
–
#GT
+B4
–
#GT
<Standard values>
1
or less
The measure-
ments meet
the standard
value: Go to
YES.
The measure-
ments do not
meet the stan-
dard value: Go
to NO.
Go to step 3.
Repair or
replace the
battery power
supplying cir-
cuit (harness,
fuse etc).
Perform "After-
inspection
work" of
INFORMA-
TION section.
Summary of Contents for 238
Page 201: ...ENGINE CONTROL SYSTEM J08E 4 978 Harness disconnection or short circuit ...
Page 215: ...ENGINE CONTROL SYSTEM J08E 4 992 Malfunction of sensor 2 Malfunction of engine ECU ...
Page 301: ...ENGINE CONTROL SYSTEM J08E 4 1078 8 Estimated failure factors Malfunction of engine ECU ...
Page 709: ...DEF SCR SYSTEM DCU 5 143 8 Estimated failure factors DEF pump pressure sensor malfunction ...