Fault Phenomenon: XCMG LW300 wheel loader after the engine is turned off, the intake heater continues to operate, causing battery drain and potentially burning the harness.

Troubleshooting Process:
– Checked relay: intake preheat relay contacts welded, unable to open.
– Checked switch: key switch or preheat switch faulty.
– Checked wiring: control wire shorted to power.
– Checked heater: heating grid itself normal.

Root Cause: The intake preheat relay contacts welded due to excessive current or aging, failing to cut off power.

Required Parts: Replace intake preheat relay.