Yanmar 3TNV82A Troubleshooting Manual page 168

FAILURE DIAGNOSIS
Work Description
1. Check of the sensor resistance value (sensor only):
• Remove the harness from the speed sensor.
• Measure the resistance between speed sensor terminals A and B using a circuit tester.
(REF) Coil resistance value of Yanmar standard speed sensor
NG
OK
2. Check of the sensor resistance value (sensor + harness):
• Connect the speed sensor and the harness, and remove E-ECU from the harness.
• Measure the resistance between harness side E-ECU connector terminals E19 and E18 using a circuit
tester.
*See above-mentioned "(REF) Coil resistance of Yanmar standard speed sensors".
NG
OK
3. Check of harness continuity:
• Remove the speed sensor and E-ECU from the harness.
• Check the harness continuity using a circuit tester.
Terminal
Sensor signal (+) wire E19
[Between E-ECU and sensor connector]
Sensor signal (-) wire E18
[Between E-ECU and sensor connector]
Between E19 and GND/E45/E47
(between E18 and GND/E45/E47)
NG
OK
1-166
Terminal
Sensors A - B
Replace the speed sensor.
Check the resistance between sensor terminals A and B with the speed sensor and
the harness being connected. → Go to [2. Check of the sensor resistance value
(sensor + harness):]
Replace the harness.
Check the harness for correct continuity. → Go to [3. Check of harness continuity:]
• Check if the harness is damaged, or if the wiring is correct.
• Replace the harness.
Replace E-ECU.
Method and Procedure of Failure Diagnosis
Continuity
Available OK: normal
Unavailable NG: harness disconnection
Available OK: normal
Unavailable NG: harness disconnection
Unavailable OK: normal
Available NG: harness short-circuited with GND
TNV DI Service Manual
Specification
500 ± 100Ω
Status