Cooling fan
Common VFD, drive, UPS, and cabinet overheating failure point.
Okuma CNC Alarm 4000 - What It Means
Okuma Alarm 4000 indicates a safety circuit error - the machine’s safety monitoring function detected an abnormal condition in the safety-related circuits. The Okuma OSP safety monitor continuously checks E-stop circuits, door interlocks, and axis safety functions; Alarm 4000 fires when any of these checks fail or detect an inconsistency.
Common Causes
- E-stop circuit fault - An E-stop button is stuck, a contact has failed, or the safety relay for the E-stop circuit has an internal fault.
- Safety door interlock fault - A machine door interlock switch has failed or the door isn’t fully closed and latched. Okuma machines have multiple safety door circuits.
- Safety relay or contactor fault - The safety relay or contactor in the safety circuit has a welded contact or coil failure.
- OSP safety function parameter issue - On newer Okuma OSP machines with integrated safety functions, a parameter or firmware issue can cause Alarm 4000.
Step-by-Step Fix
- Check all E-stop buttons - Physically inspect and twist-release all E-stop buttons on the machine and any connected pendants or remote stations. A stuck button causes Alarm 4000.
- Verify all door interlocks - Close and latch all machine doors and guards. Check door safety switches for correct operation (they should show as closed when doors are latched in the Okuma diagnostics).
- Check safety relay status - Open the control cabinet and inspect the safety relay LEDs. A safety relay with a red LED or no LED indicates a tripped or failed relay.
- Power cycle - After verifying all E-stops are released and doors are closed, cycle main power for a clean restart.
- Contact Okuma - Alarm 4000 that persists after full E-stop and door check requires Okuma factory-trained service. Safety circuit work must be done by qualified personnel.
Parts Often Needed
| Part | Notes |
|---|---|
| Safety relay module | Replace if relay won’t reset or has failed contacts |
| Door interlock switch | Replace if switch won’t confirm door closed |
| E-stop button | Replace if button mechanism is stuck |
Need Replacement Parts?
Before ordering, match the machine-control part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.
When to Call a Pro
Never bypass or jumper safety circuit components to clear Alarm 4000. Okuma authorized service should diagnose and repair all safety circuit faults.