Quick answer
- Nine times out of ten it's the battery, not the tool. Swap in a different charged 20V MAX pack before anything else.
- Clean the battery contacts and the rails inside the tool. Grit and corrosion there mimic a dead driver.
- Check the forward/reverse collar isn't stuck in the center position, which locks the trigger on purpose.
- If a hot tool just quit, let it cool. The DCF887 backs off when it overheats and comes back once it's cool.
Symptoms and what they point to
A DeWalt impact driver "not working" shows up a few different ways, and each points somewhere. Dead silence with a full battery usually means a contact or trigger problem. A tool that runs then fades under load points at a tired or overheated battery. Clicking with no rotation is often the forward/reverse collar or a bit-retention issue, not the motor. Knowing which symptom you've got saves you tearing into the wrong thing.
One myth to kill first: the DCF887 and the other XR impact drivers are brushless. There are no motor brushes to wear out or replace, so any advice telling you to swap brushes on these is for an older brushed tool, not yours.
Start with the battery
This is the fix most of the time, so do it properly.
- Try a known-good pack. Put a different fully charged 20V MAX battery in the tool. If it runs, your original pack is the problem, not the driver.
- Check the pack's fuel gauge. Press the button on the battery. If the lights are dim or it won't show a full charge after a long sit on the charger, the cells are tired.
- Mind the temperature. Lithium-ion won't charge below roughly 32°F (0°C). That's a normal safety interlock, not a fault. A battery left in a cold truck may simply need to warm to room temperature before it'll charge or run.
- Seat it fully. Push until it clicks firmly. A pack that's a hair loose can read as completely dead.
Then the contacts and trigger
If a fresh battery doesn't fix it, look at the connection between pack and tool. Pop the battery off and inspect the terminals on both the pack and the rails inside the tool. Sawdust, drywall grit, and corrosion build up there and break the circuit. Blow it out with compressed air and gently clean the contacts. Don't bend the terminals.
The trigger switch is the next suspect, and it's a known weak point on these drivers. If the tool works intermittently, cuts out when you ease off, or only runs at full speed, the variable-speed switch is likely worn or gummed up. Working the trigger fully a few dozen times sometimes frees a sticky one. A genuinely failed switch is a replaceable part, but at that point many people weigh the repair against the tool's age.
The thing people miss
Check the forward/reverse collar. That button above the trigger has a center detent that locks the trigger so the tool can't fire by accident in your bag. If it's parked halfway, the driver is dead by design. Click it fully to forward or reverse and try again. It sounds too obvious to mention, and it's caught plenty of people who were about to send a perfectly good tool in for service.
If the tool quit mid-job and got hot, set it down for ten minutes. Heavy driving into dense material trips the tool's thermal protection, and it returns on its own once the temperature drops.
When it's actually broken
If a known-good battery, clean contacts, and a confirmed-forward collar still get you nothing, the failure is inside the tool, usually the switch or the electronic control. DeWalt's warranty runs three years on these, so check your purchase date before you open it up. In many cases a tool under warranty gets replaced rather than repaired, so start with DeWalt support before you order parts.