Fault Phenomenon: Caterpillar 777 mining truck the dump body does not stop when raised to the top, causing hydraulic hose bursts or structural damage.

Troubleshooting Process:
– Checked limit switch: mechanical limit switch contacts welded or damaged.
– Checked wiring: wiring shorted.
– Checked control valve: hoist control valve spool stuck.
– Checked controller: ECU logic error.

Root Cause: The dump body hoist limit switch failed, failing to send a stop signal to the control valve, causing the pump to continue supplying oil.

Required Parts: Replace dump body hoist limit switch.