Fault Phenomenon: Komatsu WA470 wheel loader turning the key, the starter motor does not respond, instrument lights not on.

Troubleshooting Process:
– Checked battery: low battery power or loose/oxidized terminals.
– Checked fuse: main power fuse blown.
– Checked starter relay: relay coil burnt.
– Checked emergency stop button: emergency stop not reset.

Root Cause: The emergency stop button in the cab was accidentally pressed and not reset, cutting off the main power circuit.

Required Parts: Reset emergency stop button, clean battery terminals.