Yanmar 6LY3 series Service Manual page 332

TROUBLESHOOTING
Case 1: When the DTC is ACTIVE
To identify the cause (wire harness, sensor failure or connector)
1. Check the sensor performance using the following:
Measure the resistance between both terminals of the temperature sensor (with the sensor connector
disconnected).
Check if the resistance is within normal range. (See Sensor Specification Chart on page 13-34.)
Faulty Replace sensor.
OK Check ECU / wire harness output voltage.
NOTICE: If a known good sensor is available, unplug the connector from the sensor that is indicating an
active DTC fault code and reconnect to the known good sensor. See if an alarm goes off or not.
Alarm goes off?
Yes
No
The temperature is logged by the YDT.
2. Checking the ECU / wire harness output voltage:
• Unplug the connector from the temperature sensor. Leave the ECU connector connected to the ECU.
• Turn the key to ON and supply power to the ECU.
• Measure the voltage. Check the voltage between the terminals of the wire harness connector.
Wire Harness Connector
Failure Check the engine wire harness.
OK Check the sensor voltage output.
3. Checking the wire harness open / short circuit.
• Disconnect the ECU connector from the ECU and unplug the sensor connector.
• Use an electric tester to check for an open / short circuit in the wire harness (continuity).
C: 5V sensor supply
Terminals
[ECU_TH] - A
[ECU_G_S] - B, ECU Pin #35
[ECU_TH] - other terminal / ground
[ECU_G_S] - ground / 11 / 33 / 34, ECU Pin #35
13-42
Sensor failure. Replace the sensor.
Check the ECU / wire harness output voltage.
Terminals
A - B
© 2007 Yanmar Marine International
Troubleshooting by DTC Fault Codes
Contents
Continuity
Good OK: Normal
Defective
Failure: Open circuit
Good OK: Normal
Defective
Failure: Open circuit
Defective OK: Normal
Good
Failure: Short circuit
Good OK: Normal
Defective
Failure: Short circuit
6LY3 Service Manual
Value
5V
Status