the led worklight on my makita impact stays on all the time even with the battery out, it just slowly fades, what's going on?

Diagnosis

The behavior you are seeing in your Makita XDT16Z is caused by the discharge of the electrolytic capacitors located on the internal printed circuit board (PCB). Capacitors act as temporary energy reservoirs, smoothing out voltage spikes and providing a steady stream of current to the electronic components. In the XDT16Z, the LED worklight is wired into the circuit in a way that it can draw the remaining residual energy stored in these capacitors once the primary 18V LXT battery source is removed. When you slide the battery out, the circuit is broken, but the capacitors still hold a specific amount of electrical charge. Because the LED requires very little current to illuminate, it continues to draw from this reserve until the voltage drops below the LED's forward-voltage threshold, resulting in the "slow fade" effect. This is a standard characteristic of the XDT16Z's circuit design and does not indicate a short circuit or a failing component. You can confirm this is normal if the light fades out within 10 to 20 seconds; if the light remains bright for several minutes, it may indicate a parasitic draw or a faulty capacitor.

How to Fix It

Since this is a result of stored electrical energy and not a mechanical failure, there is no part to replace. However, if you need the light to turn off immediately for storage or transport, follow these steps to manually bleed the capacitors:

1. Remove the 18V LXT battery pack completely from the base of the tool.
2. Ensure the tool is set to the "Reverse" or "Forward" position (the specific direction does not matter for this process).
3. Squeeze and hold the trigger switch fully for 3 to 5 seconds. This forces the remaining energy in the capacitors to be sent toward the motor windings, which consumes the energy much faster than the LED does.
4. Release the trigger. The LED worklight should now be completely extinguished.
5. Reinsert the battery when you are ready to resume work.

If That Didn't Work

If the LED persists in staying lit for an abnormal amount of time (over 60 seconds) or refuses to fade, consider these alternatives:

• Check for conductive debris in the battery terminal rails. Metal shavings or sawdust mixed with moisture can create a high-resistance bridge between the positive and negative terminals, which can cause erratic electrical behavior or slow discharges. Use a can of compressed air to blow out the battery port.
• Inspect the trigger switch for "sticking." If the trigger is not returning fully to the neutral position due to grit or debris, it may be keeping the circuit partially closed, which can affect how the capacitors discharge. Use a non-residue electronic contact cleaner around the edges of the trigger assembly.
• Perform a "hard reset" of the internal logic. Leave the battery out of the tool for at least 24 hours. This allows the capacitors to discharge naturally through the board's own internal leakage current, which can sometimes clear "ghost" currents in the circuitry.
• Verify the battery health. If you are using an older, non-Star Protection battery, voltage fluctuations can sometimes cause the capacitors to overcharge. Try the tool with a fresh, fully charged BL1850 or BL1830 pack to see if the fade duration changes.

Heads Up

• Avoid using high-pressure solvents or water to clean the battery terminals, as this can damage the PCB and lead to actual short circuits that could blow the internal fuse.
• Never attempt to bridge the battery terminals with a screwdriver or metal object to "drain" the tool; always use the trigger switch as described in the fix section.
• The XDT16Z is a brushless tool; be aware that the electronic controller (ESC) is sensitive to static discharge. Always handle the tool in a dry environment.
• If you notice the tool housing feeling warm to the touch while the battery is removed and the light is on, stop using the tool immediately and have the PCB inspected for a short.