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Fault code
Meaning of the fault code
(Hex)
possible reason for fault detection
77
S.C. to battery voltage at clutch K3
The measured resistance value of the
valve is out of limit, the voltage at K3 valve
is too high
Cable/connector is defective and has
contact to battery voltage
Cable/connector is defective and has
contact to another regulator output of the
TCU
Regulator has an internal defect
78
S.C. to ground at clutch K3
The measured resistance value of the valve
is out of limit, the voltage at K3 valve is too
low
Cable/connector is defective and has
contact to vehicle ground
Regulator has an internal defect
79
O.C. at clutch K2
The measured resistance value of the
valve is out of limit
Cable/connector is defective and has no
contact to TCU
Regulator has an internal defect
7A
S.C. to battery voltage at converter
clutch
7B
S.C. to ground at converter clutch
7C
O.C. at converter clutch
7D
S.C. ground at engine derating device
Cable is defective and is contacted to
vehicle ground
Engine derating device has an internal
defect
Connector pin is contacted to vehicle
ground
7E
S.C. battery voltage at engine derating
device
Cable/connector is defective and is
contacted to battery voltage
Engine derating device has an internal
defect
Reaction of the TCU
TCU shifts to neutral
OP mode : Limp home
If failure at another clutch is
pending
TCU shifts to neutral
OP mode : TCU shutdown
TCU shifts to neutral
OP mode : Limp home
If failure at another clutch is
pending
TCU shifts to neutral
OP mode : TCU shutdown
TCU shifts to neutral
OP mode : Limp home
If failure at another clutch is
pending
TCU shifts to neutral
OP mode : TCU shutdown
-
-
-
Engine derating will be on until
TCU power down even if fault
vanishes(Loose connection)
OP mode : Normal
No reaction
OP mode : Normal
3-22
Possible steps to repair
Check the cable from TCU to the
gearbox
Check the connectors from
gearbox to TCU
Check the regulator resistance*
Check internal wire harness of the
gearbox
* See page 3-36
Check the cable from TCU to the
gearbox
Check the connectors from
gearbox to TCU
Check the regulator resistance*
Check internal wire harness of the
gearbox
* See page 3-36
Check the cable from TCU to the
gearbox
Check the connectors from
gearbox to TCU
Check the regulator resistance*
Check internal wire harness of the
gearbox
* See page 3-36
-
-
Not used
Check the cable from TCU to the
engine derating device
Check the connectors from engine
derating device to TCU
Check the resistance* of engine
derating device
Not used
* See page 3-36
Check the cable from TCU to the
engine derating device
Check the connectors from
backup alarm device to TCU
Check the resistance* of backup
alarm device
* See page 3-36
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