How to Solve JCB 140 Excavator Swing Lock Solenoid Short Circuit
C0391-11:Swing lock solenoid short circuit to Ground. Possible
Preparations:
2025 JCB ServiceMaster 4 v25.1.0
2017 JCB Parts Plus+ and Repair Service Manual
JCB Diagnostic Kit
Cause:
1. MECU high side Output & Low side Output short circuited in wire harness.
2. MECU High Output wire connected to machine ground.
3. Faulty Solenoid. 
Diagnosis:
1. Check the connectivity between circuit no 8049 & 4049 through by help of multimeter after disconnecting the swing lock solenoid. Refer below photograph.
2. Check the connectivity between circuit no 8049 & machine earth by help of multimeter when swing lock solenoid disconnected from wire harness. Refer below photograph.
3. Check the solenoid coil circuit resistance. The resistance of solenoid coil shall be 37Ω. Corrective Action:- 1. Replace the faulty wire harness. 2. Replace faulty solenoid coil.
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