my makita angle grinder just stopped spinning mid-cut, trigger feels normal but nothing happens.

Diagnosis

The sudden cessation of motor rotation during a cut on the Makita XAG04Z is typically caused by one of two failures: a burnt-out trigger switch or the activation of the electronic overload protection circuit. Because the trigger still "feels" normal (meaning the physical spring tension is intact), the failure is electrical rather than mechanical. In high-torque applications, the switch contacts can arc and weld shut or, more commonly, carbonize and create an insulating layer that prevents current from reaching the motor. Alternatively, if the tool stopped abruptly during a heavy cut, the internal thermal overload protection may have tripped. This occurs when the motor windings overheat or the gear head encounters too much resistance, causing the control board to cut power to prevent the motor from melting. You can confirm a switch failure if the tool remains dead across multiple fully charged 18V LXT batteries, whereas a thermal trip usually resets after 15-30 minutes of cooling. If the tool is completely silent with no "click" or hum from the motor, the electrical path from the battery terminal to the armature is broken.

How to Fix It

To resolve a failed trigger switch, you will need a replacement switch assembly (Part No. 192059-5) and a T10 Torx driver. Follow these precise steps:

1. Remove the 18V LXT battery immediately to ensure the tool is completely depowered.
2. Using a T10 Torx driver, remove the four recessed screws located on the rear plastic housing of the grinder.
3. Carefully pry the two halves of the housing apart. Be cautious not to pinch the wiring harness between the plastic shells.
4. Locate the switch assembly. Note the exact routing of the red and black wires to ensure they are not pinched during reassembly.
5. Disconnect the wires from the old switch. If they are soldered, use a soldering iron to desolder the joints; if they are crimped, use needle-nose pliers to slide the connectors off the terminals.
6. Remove the failed switch assembly from its molded plastic seat.
7. Insert the new 192059-5 switch, ensuring the trigger lever is properly seated in the housing notch.
8. Connect the wires to the corresponding terminals on the new switch, ensuring a tight, secure fit to prevent future arcing.
9. Before closing the case, manually rotate the motor shaft to ensure no wires are obstructing the armature.
10. Rejoin the housing halves and tighten the four T10 screws in a cross-pattern to ensure even pressure on the seal.

If That Didn't Work

• Check the Battery Terminal Contacts: Inspect the battery slots on the tool. If the copper tabs are bent or corroded, the tool may lose contact mid-cut due to vibration. Use a small file or sandpaper to clean the contacts and gently bend them back to ensure a tight grip on the battery.
• Inspect the Carbon Brushes: While the XAG04Z is a brushless-style design in some regions, many LXT grinders still utilize brushes. If the brushes have worn down to the limit, the spring can no longer push them against the commutator, causing the tool to stop. Check for excessive sparking or a "dead spot" in the motor rotation.
• Test the Battery Cell Balance: A failing 18V LXT battery may show a full charge on the LED indicator but suffer a voltage drop under load. Test the tool with a known-working 5.0Ah or 6.0Ah battery to rule out a cell collapse in your current battery pack.
• Examine the Gear Head for Seizure: If the motor hums but doesn't spin, the bearings in the gear head may have seized due to metal dust ingress. Try rotating the spindle by hand (with the battery removed); if it is locked or feels "gritty," the gear assembly needs a full teardown and regreasing.

Heads Up

• Dust Management: Angle grinders suck in massive amounts of conductive metallic dust. Every 6 months, use compressed air to blow out the motor vents to prevent the switch and PCB from shorting out.
• Avoid "Deep-Loading": If the tool stops during a cut, do not immediately force the trigger. Let the tool idle for 30 seconds to allow the electronic overload protection to reset.
• Battery Pairing: Always use genuine Makita LXT batteries. Third-party "knock-off" batteries often lack the proper communication chips, which can cause the tool's internal protection circuit to trip prematurely.
• Wire Routing: When reassembling the housing, ensure the wires are tucked into their designated channels. A pinched wire can create a short circuit that will permanently fry the motor controller.