RED/GREEN FLASH (ALTERNATING)
Milwaukee
Battery Pack Communication Fault
Vacuum will not run; LED on the tool alternates red and green when trigger is pulled.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Damaged M18 battery pack data pins, Corroded or bent battery contacts in vacuum, Faulty battery management PCB in vacuum handle, Incompatible or non-genuine Milwaukee battery
How to Fix / Troubleshooting
Safety first: Remove the battery pack from the vacuum before inspecting anything. Do not short battery terminals.
- 1. Inspect battery pack: Check the M18 battery terminals and data pins for corrosion, burning, or physical damage. Clean light oxidation with a dry nylon brush; do not use water.
- 2. Check tool battery rails: Look into the battery slot on the vacuum. Ensure the metal contacts are straight, springy, and not recessed. Gently bend back into position with a non‑conductive tool if slightly bent.
- 3. Try another known-good battery: Use a fully charged, genuine Milwaukee M18 pack. If the error clears, the original battery is likely faulty.
- 4. Reset electronics: Remove the battery for 60 seconds, then reinsert and test. Sometimes the control PCB will reset.
- 5. If still flashing: The vacuum’s internal control PCB or battery interface board may be defective. Do not bypass safety circuits. Contact a Milwaukee service center for PCB replacement.
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Repair Difficulty
Medium
3/5
Required Part
Battery Contact Assembly / Control PCB
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