P0686/4: Main Relay Error - Yanmar 3TNV82A Troubleshooting Manual

FAILURE DIAGNOSIS

(3) P0686/4: Main relay error

DTC P0686/4
DTC Detecting Conditions
1 - Precondition; 2 - Detecting condition(s); 3 - Flashing pattern of failure indicator
1. Key switch OFF.
2. Power supply to ECU fails to turn OFF.
3. One flash followed by six flashes.
Movement at Error occurrence
Error Mode [Run As Is]:
After detecting the error, the system lets the engine continue to run without any
restrictions.
Run restricted? No.
Recovery No.
Conditions
Remarks
Estimation of Failure cause/Error condition
• The connector may not be properly connected.
• Wiring defect of the harness
Downstream line of the main relay coil may be short-circuited with GND or POWER SUPPLY (*NOTE).
•
• The main relay contact may be faulty.
The main relay contact may be stuck.
•
Inner wiring of the main relay coil short-circuited with POWER SUPPLY (*NOTE).
•
*NOTE) If the downstream line of the main relay coil is short-circuited with POWER SUPPLY, the E-ECU's
power supply line fuse 10A may be blown or the inner circuit of E-ECU may fail.In this case, the E-
ECU may fail to detect/indicate the error, and to store the error history.
• The E-ECU internal circuitry may be faulty.
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DTCs (Diagnostic Trouble Codes) General Description
Main relay error
Check points
Connector
Harness
Main relay
TNV DI Service Manual