Dryer drum light stays on even when the door is closed, or never comes on at all.

Safety first: Unplug the dryer before replacing bulbs or switches.

• Test door switch: Press the switch manually with the door open; the light should turn off/on. If not, test continuity and replace if faulty.
• Replace bulb: If your model uses a replaceable bulb, remove the cover and install a new bulb of the specified type.
• Check wiring: Inspect the harness from the switch to the light and control board for loose connections.
• Control board: If the switch and bulb are good but the light still misbehaves, the control board may be at fault and require professional service.