SEN00460-01 40 Troubleshooting
38 114E-3 Series
E-47 Code [778/CA778] Eng. Bkup Speed Sensor Error 1
Error code Failure code
Trouble Abnormality in engine Bkup speed sensor
778 CA778
Contents of
trouble
• Abnormality is detected in signals of engine Bkup speed sensor.
Action of con-
troller
• Controls with signals of Ne speed sensor.
Problem that
appears on
machine
• Starting performance is poor
• Output drops.
Related infor-
mation
• Method of reproducing failure code: Start engine.
Possible causes
and standard
value in normal
state
Causes Standard value in normal state/Remarks on troubleshooting
1
Defective sensor power sup-
ply 2 system
If failure code [CA187] is indicated simultaneously, carry out trouble-
shooting for it first.
2
Defective engine Bkup speed
sensor
a Prepare with starting switch OFF, then turn starting switch ON and
carry out troubleshooting.
CAM SENSOR Voltage
Between (1) – (2) Power supply 4.75 – 5.25 V
Voltage is measured with wiring harness connected. Accordingly, if
voltage is abnormal, check wiring harness and controller, too, for
another cause of trouble, and then judge.
3
Broken engine Bkup speed
sensor or defective clearance
Inspect engine Bkup speed sensor directly for breakage or clear-
ance.
4 Broken rotation sensing ring Inspect it for breakage directly.
5
Disconnection in wiring har-
ness (Disconnection in wiring
or defective contact in con-
nector)
a Prepare with starting switch OFF, then carry out troubleshooting
without turning starting switch ON.
Wiring harness between J1 (female) (26) –
CAM SENSOR (female) (3)
Resis-
tance
Max. 10 z
6
Ground fault in wiring har-
ness (Short circuit with GND
circuit)
a Prepare with starting switch OFF, then carry out troubleshooting
without turning starting switch ON.
Wiring harness between J1 (female) (26) –
CAM SENSOR (female) (3)
Resis-
tance
Min.
100 kz
7
Hot short (Short circuit with
5V, 24V circuit) in wiring har-
ness
a Prepare with starting switch OFF, then turn starting switch ON and
carry out troubleshooting.
Wiring harness between J1 (female) (26) –
CAM SENSOR (female) (3)
Voltage Max. 1 V
8
Short circuit in wiring harness
(With another wiring harness)
a Prepare with starting switch OFF, then carry out troubleshooting
without turning starting switch ON.
Wiring harness between J1 (female) (26) –
CAM SENSOR (female) (3) and J1 (female)
(37) – CAM SENSOR (female) (1)
Resis-
tance
Min.
100 kz
Wiring harness between J1 (female) (26) –
CAM SENSOR (female) (3) and J1 (female)
(47) – CAM SENSOR (female) (2)
Resis-
tance
Min.
100 kz
9
Defective wiring harness
connector
Connecting parts among engine Bkup speed sensor, engine wiring
harness, and engine controller are suspected. Inspect them directly.
• Loose connector, broken lock, broken seal
• Corrosive, bent, broken, forced-in, or extended pin
• Humidity in connector, entry of dirt or dust, poor insulation
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