the led work light on the front of my saw won't turn on anymore

Diagnosis

The Ryobi ONE+ 18V Reciprocating Saw P519 is designed for high-vibration demolition work, which is the primary enemy of the LED work light circuitry. Because the LED is positioned at the very front of the tool—the area experiencing the most violent oscillation—the most common failure point is not the diode itself, but the solder joints connecting the two thin-gauge power wires to the LED board. Over time, the constant shaking causes "work hardening" of the copper wires, leading them to snap right at the solder point or pull away from the PCB entirely. Another frequent cause is a failure in the trigger-integrated switch. In the P519, the LED is wired to activate simultaneously with the motor. If the light is out but the saw still cuts, the issue is localized to the LED wiring harness or the diode. However, if the saw is also intermittent, the problem lies in the main trigger switch assembly. You can confirm a wiring failure by opening the housing and using a multimeter to check for continuity between the trigger output and the LED terminals while the trigger is depressed.

How to Fix It

To resolve this, you will need to perform a surgical repair of the internal wiring. You will need a Phillips #2 screwdriver, a soldering iron (15-30W), and a small amount of 60/40 rosin-core solder.

1. **Safety First:** Remove the 18V ONE+ battery pack immediately. Never perform internal repairs with the battery seated, as you risk shorting the main board.
2. **Disassemble the Chassis:** Locate the four primary housing screws on the side and bottom of the tool. Remove these and carefully pull the two halves of the plastic shell apart. Be mindful of the trigger assembly; do not yank the shells apart, as the trigger spring may pop out.
3. **Inspect the LED Module:** Locate the LED board situated directly behind the clear plastic lens at the nose of the tool. Look for the two thin wires (typically red and black) connecting the board to the main wiring loom. Check for any visible breaks or wires that are hanging loose.
4. **Resolder Connections:** If a wire has detached, strip a tiny fraction of the insulation (about 2mm) from the wire end. Using your soldering iron, heat the copper pad on the LED board and the wire simultaneously, applying a small bead of solder to create a permanent bond.
5. **Secure the Wiring:** To prevent this from happening again, use a small piece of electrical tape or a zip-tie to secure the LED wires to the rest of the internal wiring harness. This creates a "strain relief" so that vibration doesn't pull directly on the solder joints.
6. **Reassemble and Test:** Carefully align the two halves of the shell, ensuring the trigger is seated correctly in its slot. Reinsert the four screws and slide in the battery to test the light.

If That Didn't Work

• **Check the Trigger Switch:** If the wiring is intact, the internal contact for the LED within the trigger switch may have failed. Since the trigger is a sealed unit, you cannot easily repair it. You will need to replace the entire trigger switch assembly (Part #RS12000 or equivalent for the P519 series).
• **Bypass the Board:** If the LED diode itself has burned out (rare but possible), you can replace the small LED board with a generic 18V-compatible high-brightness LED. Ensure the polarity is correct (positive to positive) or the light will not illuminate.
• **Inspect the Battery Terminals:** Check the battery contact pins on the saw. If there is corrosion or a bent pin, the tool may have enough current to run the motor but not enough stable voltage to trigger the LED circuit. Clean the contacts with a cotton swab and isopropyl alcohol.
• **Check for Internal Shorts:** Inspect the main circuit board for any "scorched" components or melted plastic. If the tool was used in extremely wet conditions, a short circuit may have blown the LED trace on the PCB.

Heads Up

• **Avoid Over-tightening:** When reassembling the housing, do not over-torque the plastic screws. The P519 housing is prone to stripping, which will lead to the tool vibrating even more, potentially breaking the light again.
• **Debris Management:** While the saw is open, use compressed air to blow out the sawdust and drywall dust from the motor housing. This prevents overheating and extends the life of the trigger switch.
• **Wire Routing:** Ensure that the LED wires are routed away from the reciprocating shaft and the gear housing. If a wire rubs against the moving mechanical parts, it will eventually chafe through and short out.
• **Battery Care:** Always store your ONE+ batteries in a cool, dry place. Extreme heat can degrade the cells, leading to voltage drops that cause LED flicker or premature failure of the tool's electronic components.