my makita xdt16z impact driver just stopped working mid-job, no lights, no sound, nothing when i pull the trigger.

Diagnosis

The total loss of power in the Makita XDT16Z—characterized by a lack of LED indicator lights and no mechanical response from the trigger—typically indicates a complete break in the electrical circuit between the battery cells and the motor controller. Since this happened mid-job, the most likely culprit is a "tripped" battery protection circuit or a failure in the tool's internal trigger switch assembly. If the LED lights on the tool are completely dark, the tool is not receiving any voltage. This can be caused by carbon buildup on the battery terminals, a blown internal fuse within the battery pack (often triggered by an accidental short or extreme overheating), or a failure of the trigger switch's micro-switch. To confirm, check the battery's own onboard charge indicator; if the battery light works but the tool light does not, the issue is isolated to the tool's terminals or the internal wiring. If neither the battery nor the tool lights up, the battery pack has likely entered a "sleep" or "protection" mode due to critical voltage drop.

How to Fix It

Follow these steps in order to isolate the electrical failure and restore power to the unit:

1. Perform a Hard Reset: Remove the battery pack and hold the trigger down for 30 seconds. This drains any residual capacitance in the motor controller and resets the internal logic.
2. Clean the Contact Points: Use a cotton swab dipped in 90% isopropyl alcohol to clean the three metal terminals inside the tool's battery shoe. Inspect for any blackened carbon deposits or bent pins that may be preventing a flush connection.
3. Test with a Known-Good Pack: Swap the current battery for a fully charged 18V LXT battery (preferably a 5.0Ah or 6.0Ah pack). If the tool fires up, the previous battery has suffered a cell failure or a tripped BMS (Battery Management System).
4. Verify the Forward/Reverse Toggle: Ensure the direction selector is clicked fully into one of the two directions. If the toggle is stuck in the center "neutral" position, the trigger is electronically locked and will not engage the motor or lights.
5. Inspect Battery Rails: Check the plastic rails on the battery pack for debris or sawdust. If the battery isn't clicking fully into place, the terminal pins won't make full contact with the tool's internal bridge.

If That Didn't Work

• Check for a Blown Internal Fuse: If you have a multimeter, set it to DC voltage and probe the battery terminals. If you read 0V despite the battery being "charged," the internal fuse of the battery pack has blown. This is common if the tool was dropped while the battery was inserted, causing a momentary short. The battery pack will need to be replaced.
• Trigger Switch Replacement: The trigger assembly on the XDT16Z is a modular component. If the tool remains dead with multiple batteries, the micro-switch inside the trigger has likely failed. You will need to disassemble the housing and replace the trigger switch assembly (Part # varies by region, but look for the XDT16 series switch).
• Inspect the Brushless Controller (PCB): Open the tool casing and look for any scorched components or "burnt" smells coming from the circuit board. If a capacitor has popped or a trace has burned out due to overheating during a heavy-duty task, the PCB will need to be replaced.
• Wire Continuity Test: Use your multimeter to check for continuity between the battery terminals and the motor leads. A pinched or severed wire inside the handle—often caused by excessive vibration or tool drops—can cause a total power loss.

Heads Up

• Avoid "Deep Discharge": Never store your LXT batteries when they are completely drained; this can trigger the permanent protection circuit, rendering the battery "dead" even if the charger says it is full.
• Temperature Management: If the tool stops during a high-torque application, it may be in thermal shutdown. Let the tool cool for 15 minutes before attempting to restart.
• Terminal Care: Never use conductive lubricants or WD-40 on the battery terminals, as this attracts metallic dust and can cause a short circuit.
• Proper Seating: Always listen for the audible "click" when inserting the battery. A loose fit leads to arcing, which carbonizes the terminals and causes the exact power loss described here.