Kubota E:9110 – Main ECU: Main relay system error
Issue description
Indicates an error in the 'Main relay system'. The system has detected a malfunction, voltage irregularity, or communication failure involving the main electrical relay that powers the machine's primary control systems.
Applies to these machines
10 machines- SVL65-2
- SVL75
- SVL75-2
- SVL95-2s
- SVL97-2
- SSV65
- SSV75
- R430
- R530
- R630
Check the cause
Verify the battery is fully charged and the terminals are clean and tight.
Check the main chassis grounds and the ground wire leading to the starter relay and ignition switch.
Inspect the main wire harness (specifically around the cab relay/ECU box) for broken wires, rodent damage, or loose connectors.
Locate the main relay block and test the main relay for continuity and proper switching when the ignition is turned on.
Test the ignition switch to ensure it is sending the correct voltage to the main relay when turned to the 'ON' position.
Repair steps
Disconnect Power
Always disconnect the negative battery cable before servicing the electrical system.
Locate the Relay/ECU Panel
Access the electrical panel (usually located inside the cab behind the access panel or under the seat, depending on the specific SVL/SSV model).
Inspect and Replace the Relay
Pull the main relay. Check the socket for melted plastic or corrosion. If the relay is faulty, replace it with a new OEM relay.
Check the Main ECU
If the relay and wiring are intact but the code persists, the Main ECU may have an internal fault in its relay control circuit.
Reassemble and Clear Codes
Reconnect the battery, turn the ignition on, and verify if the code clears. If a new ECU was installed, it may require dealer programming (Diagmaster software) to sync with the machine.
Parts you might need
(5)Main ECU (Engine Control Unit)
V0631-53726Main ECU (Engine Control Unit)
V0631-53725Main ECU (Engine Control Unit)
V0631-53722- 12V Relay (Heater / Main Power)3N300-75213
Main Wire Harness
B40804
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