Doosan CNC Fault Codes — Complete Troubleshooting Guide

Doosan CNC machines — PUMA lathes, LYNX lathes, DNM vertical machining centers, and DVF 5-axis — run Fanuc 0i, 18i, 21i, or 31i controls with a Doosan-specific PMC (Programmable Machine Controller) layer on top. When an alarm fires, you’re looking at either a Fanuc servo/system alarm (numbered below 1000) or a Doosan PMC alarm (2000-series). Both types appear on the same Fanuc display and require different diagnostic approaches. This guide covers both.

Jump to Section

• Alarm Categories Overview
• Accessing Alarm History
• Emergency Stop (Alarm 2001)
• Servo and Spindle Alarms
• Hydraulic Faults (2004, 2005)
• Turret Faults
• Tailstock and Chuck Faults
• ATC Faults (Tool Changer)
• Coolant and Lubrication Faults
• Spindle Faults
• Fanuc Servo Alarms (4xx, 5xx)
• Fanuc System Alarms (9xx)
• Reset Procedures
• Replacement Parts

Alarm Categories Overview

Doosan CNC alarms split into two categories displayed in different Fanuc screens:

Fanuc CNC Alarms (displayed as alarm code only):

• 0xx — Program errors (incorrect G-code)
• 1xx — Program format errors
• 4xx — Servo alarms
• 5xx — Servo/spindle communication alarms
• 7xx — Overheat alarms
• 9xx — System alarms
• PS alarms — Parameter setting errors
• OT alarms — Overtravel (axis exceeded limit)
• SV alarms — Servo axis alarms
• SP alarms — Spindle alarms

Doosan PMC Alarms (2000-series, displayed as text messages): The 2000-series alarms are generated by the Doosan PMC ladder logic. They describe machine-specific faults: hydraulic failures, turret errors, ATC malfunctions, door interlocks, and external device failures.

To display Fanuc alarms: press SYSTEM → ALARM on the Fanuc panel. To display Doosan PMC alarms: press MESSAGE on the Fanuc panel.

Accessing Alarm History

Current Alarms

1. Press MESSAGE (orange or yellow button on Fanuc MDI panel).
2. Press ALARM soft key — displays all active alarms with codes.
3. Press MSG to view PMC message history (Doosan 2000-series).

Alarm History Log

1. Press SYSTEM → soft key pages until you see ALARM HIST or ALM.HIS.
2. The Fanuc control stores the last 25 alarm events.
3. Each entry shows: alarm code, axis (if servo alarm), date/time.
4. Use this to identify recurring alarms or alarms that cleared before you arrived at the machine.

PMC Status Diagnosis

For PMC-related alarms (2000-series), access the PMC ladder to see which signal triggered the alarm:

1. Press SYSTEM → PMC → PMCLAD (or LADDER).
2. Search for the specific input signal referenced in the alarm message.
3. Check whether the relevant input (proximity switch, pressure switch, solenoid feedback) is ON or OFF.

Emergency Stop (Alarm 2001)

Alarm text: WHETHER EMERGENCY BUTTON IS PRESSED OR OVERTRAVEL OF AXES IS DETECTED, RELEASE EMERGENCY BUTTON AND LIMIT SWITCH FOR OVERTRAVEL CHECK.

Cause: The E-stop circuit has opened. This covers two conditions:

1. The physical E-stop mushroom button is pressed (at the control pendant or machine body)
2. A hardware overtravel limit switch has been activated by an axis exceeding its physical limit

Diagnosis:

E-stop button:

1. Check all E-stop buttons on the machine — panel, sub-pendant, floor button (if equipped).
2. Twist to release if latched (most buttons require clockwise twist to release).
3. Verify E-stop relay is picking up after release — check control cabinet relay labeled “ES” or “E-STOP”.

Overtravel limit:

1. Check which axis has tripped the overtravel — look at axis position display. If an axis shows an extreme value, it likely hit the limit.
2. On Fanuc: with E-stop released, hold AXIS DIRECTION OVERRIDE (if available) or use MDI to move axis away from limit. On some Doosan models, press and hold OT RELEASE button while jogging.
3. Check OT limit switch wiring and switch mechanical condition — if the switch itself is damaged, the alarm will not clear.

Reset: Release E-stop, clear overtravel if applicable, then press RESET on Fanuc panel.

Servo and Spindle Alarms

Alarm 2002: Main Spindle or Servo Unit Alarm

Alarm text: THE ALARMS OF THE MAIN SPINDLE MOTOR AND SERVO UNIT DETECTED, CHECK ALARM DISPLAY ON THE SERVO UNIT THEN RETRY AFTER POWER OFF-ON.

This alarm is a wrapper — the actual fault is displayed on the spindle drive or servo amplifier itself. Go to the control cabinet and check the alpha/beta amplifier LED display.

Fanuc amplifier display codes (common):

Diagnosis:

1. Note the drive display code before power cycling.
2. For code A (overcurrent): check motor for winding shorts or mechanical binding.
3. For code E (control power): check 24VDC supply to amplifier.
4. For code F (FSSB): inspect optical fiber cable between CNC unit and servo amplifier — even a slight bend can break the fiber.
5. For code P (phase loss): measure three-phase input to servo cabinet.

Reset: Power off machine at main breaker, wait 30 seconds for capacitors to discharge, power back on.

Alarm 2007: Spindle Rotation Abnormal

Alarm text: SPINDLE ROTATION IS ABNORMAL.

Trigger: Spindle encoder feedback does not match commanded speed within the monitoring window.

Causes:

• Spindle drive fault (check alpha spindle amplifier display)
• Encoder signal failure
• Belt slip or broken drive belt (belt-drive spindle configurations)
• Mechanical overload — heavy cut or toolholder stuck

Diagnosis:

1. Check spindle drive amplifier display code.
2. Verify spindle encoder connections at the encoder body and the alpha amplifier.
3. For belt-driven spindles: check belt condition and tension. A slipping belt shows spindle speed below commanded speed before the alarm trips.
4. Use MDI to command S500 M03 and verify spindle comes to speed.

Alarm 2027: Spindle Speed Arrival Not Detected

Alarm text: SPINDLE SPEED ARRIVAL IS NOT DETECTED WITHIN 7SEC, CHECK SPINDLE SERVO UNIT.

Trigger: The spindle has not reached commanded speed within the 7-second timeout.

Causes:

• Spindle drive fault
• Mechanical load on spindle too high (tool stuck in spindle, drawbar not releasing)
• Speed sensor (encoder) failure
• Drive parameter mismatch

Diagnosis:

1. Command S200 M03 in MDI — a lower speed is easier to achieve and narrows whether the spindle can accelerate at all.
2. Listen for mechanical noise during spindle acceleration — binding sounds indicate mechanical issue.
3. Check drawbar clamping status (if alarm occurs during tool change).

Hydraulic Faults (2004, 2005)

Alarm 2004: Hydraulic Pump Motor Overload

Alarm text: HYD. PUMP MOTOR OVERLOAD IS DETECTED, CHECK OVERLOAD VALUE ON THE THERMAL RELAY AND MOTOR.

Causes:

• Thermal relay tripped on the hydraulic pump motor
• Hydraulic pump seized or heavily loaded
• Phase loss on hydraulic pump supply
• Hydraulic oil too cold (high viscosity at startup)

Diagnosis:

1. Locate thermal relay on hydraulic pump motor in the electrical cabinet or hydraulic unit enclosure.
2. Check if thermal relay is tripped (indicator button popped out).
3. Allow motor to cool, then reset thermal relay and restart.
4. If relay trips immediately again: measure current on all three phases — overcurrent indicates pump mechanical issue.
5. Check hydraulic oil temperature — very cold hydraulic oil (below 10°C) will overload the pump motor on startup.

Reset: Press thermal relay reset button, then press machine RESET.

Alarm 2005: Hydraulic Pressure Down

Alarm text: HYD. PRESSURE IS DOWN, CHECK HYD. PRESSURE SWITCH, PRESSURE VALUE AND LEAKAGE OF HYDRAULIC.

Trigger: Hydraulic pressure switch (typically set at 30–50 bar) has not closed within the required time after the hydraulic pump starts.

Causes:

• Hydraulic pressure relief valve stuck open or set too low
• Hydraulic pump worn (low output pressure)
• Internal leakage in hydraulic actuators or valves
• Hydraulic fluid low — check reservoir sight glass
• Pressure switch faulty or set point drifted

Diagnosis:

1. Check hydraulic pressure gauge on the unit. Compare to machine specification (typically 50–70 bar).
2. Check hydraulic fluid level in reservoir.
3. Check for hydraulic leaks at cylinder ports, hose connections, and valve bodies.
4. Test pressure switch: bypass temporarily to see if alarm clears (diagnostic only — do not run with bypass).
5. If pump runs but pressure won’t build: pressure relief valve is likely stuck open or set too low. Adjust relief valve and retest.

Turret Faults

Alarm 2023: Tool Index Overtime (PUMA/LYNX)

Alarm text: TOOL INDEX OVERTIME

Trigger: Turret indexing has not completed within the allotted time.

Causes:

• Turret hydraulic clamping solenoid stuck or failed
• Turret proximity switch not detecting the indexed position
• Mechanical interference in turret — chips packed behind turret
• Hydraulic pressure insufficient for turret operation
• Turret motor drive fault

Diagnosis:

1. Check hydraulic pressure — low pressure (alarm 2005) before this alarm typically means hydraulics are causing the index failure.
2. Inspect turret area for chip buildup. Chips packed behind the turret body prevent proper seating.
3. In PMC ladder: check inputs for turret clamp and unclamp sensors. Verify the proximity switches are registering state changes during a manual turret index attempt.
4. Command a T01 in MDI and observe turret behavior. If turret starts to move then stops, the clamping mechanism is not completing.

Reset: Press RESET, verify chips are cleared, retry T01 command.

Alarm 2047: Turret Clamp Switch Error

Alarm text: TURRET CLAMP SWITCH ERROR

Trigger: Turret clamp and unclamp proximity switches have given conflicting states (both active or neither active at a moment when one should be confirmed).

Causes:

• Proximity switch misaligned or damaged
• Target disc on turret worn — sensor not detecting target at correct position
• Wiring fault on one of the proximity switches
• Turret not fully clamping/unclamping

Diagnosis:

1. In MDI, command a T01 — watch the turret closely and listen for the clamp/unclamp cycle.
2. Check PMC inputs for turret clamp switch (usually named TCLP or similar in Doosan PMC documentation).
3. Inspect proximity switch faces for damage or contamination.
4. Adjust proximity switch gap — typically 1–3mm from target face.

Alarm 2134: Turret Control Unit Alarm

Alarm text: TURRET CONTROL UNIT ALARM. CHECK SERVO CONTROL UNIT IN CONTROL CABINET.

Trigger: The servo turret drive amplifier has faulted.

Applies to: Doosan PUMA machines with servo-driven turrets (not hydraulic-indexed).

Diagnosis:

1. Check servo drive display in control cabinet — look for Fanuc servo alarm code.
2. Check motor feedback cable (encoder cable) at the turret motor and at the drive.
3. Check power supply to servo turret drive.

Tailstock and Chuck Faults

Alarm 2062: Programmable Tailstock Limit Switch Not Operated

Alarm text: LIMIT SWITCH FOR PROGRAMMABLE TAILSTOCK IS NOT OPERATED WITHIN 5SEC AFTER COMMAND, CHECK SOLENOID VALVES AND LIMIT SWITCHES.

Trigger: The tailstock has been commanded to advance or retract but the confirmation limit switch has not fired within 5 seconds.

Causes:

• Hydraulic pressure insufficient for tailstock movement
• Tailstock advance/retract solenoid valve failed
• Limit switch damaged or misaligned
• Tailstock mechanically obstructed

Diagnosis:

1. Check hydraulic pressure at tailstock circuit.
2. Verify tailstock solenoid valve operation — command tailstock advance manually from PMC or machine panel and listen for solenoid click.
3. Check limit switch position and condition at both tailstock home and advance positions.

Alarm 2046: Chuck Open During Spindle Rotation

Alarm text: CHUCK IS OPENED DURING THE SPINDLE ROTATION, CHECK HYD. PRESSURE.

Trigger: Hydraulic chuck clamping confirmation switch has dropped out during spindle rotation, indicating the chuck may have opened.

This is a safety-critical alarm. If the chuck actually opens during spindle rotation, the workpiece will be thrown. The alarm is more commonly caused by:

• Chuck confirmation proximity switch failure or misalignment
• Hydraulic pressure fluctuation causing brief pressure drop at the chuck cylinder
• Solenoid valve dither or vibration causing intermittent switch actuation

Diagnosis:

1. Stop machine immediately. Verify chuck is physically clamped on the workpiece.
2. Check hydraulic pressure stability — pressure should not fluctuate more than ±2 bar during spindle rotation.
3. Inspect chuck confirmation proximity switch. Replace if worn.
4. Check rotary hydraulic union for leakage — a worn rotary union will lose pressure to the chuck during rotation.

Alarm 2034: Proximity Switch for Chuck Clamp Position Error

Alarm text: PROXIMITY SWITCH FOR CHUCK CLAMP CONFIRM POSITION ERROR, RESET SWITCH POSITION (PX1.M) (PX2.M)

Trigger: Chuck clamp and unclamp proximity switches are both active or inactive when one confirmation is expected.

Diagnosis:

1. Check both proximity switches (PX1.M = clamp confirm, PX2.M = unclamp confirm) in PMC.
2. Manually operate the chuck footswitch — watch the switch states change on the PMC diagnostic screen.
3. Adjust proximity switch positions so only one switch is active at a time.

ATC Faults (Tool Changer)

Alarm 2103: M06 Overtime Alarm

Alarm text: M06 OVERTIME ALARM

Trigger: The M06 tool change cycle has not completed within the timeout period (typically 30–60 seconds depending on ATC type).

Causes:

• Tool stuck in spindle (drawbar not releasing)
• ATC arm not reaching position (sensor, mechanical, or pneumatic issue)
• Magazine rotation overtime (alarm 2107)
• Spindle orientation failure before tool change

Diagnosis:

1. Enter the alarm, then check active alarms for sub-alarms like 2107 (magazine rotation overtime) or 2125 (spindle clamp/unclamp alarm) — the sub-alarm identifies the specific failure point.
2. Attempt spindle orientation manually: MDI M19 and verify spindle locks at orientation angle.
3. Check ATC arm home position switch.
4. Check tool clamp/unclamp air pressure (arm and drawbar actuated by pneumatic on many Doosan ATC systems).

Alarm 2107: ATC Magazine Rotation Overtime

Alarm text: ATC MAGAZINE ROTATION OVERTIME ALARM

Trigger: Magazine rotation (tool carousel) has not completed its rotation within the allotted time.

Causes:

• Magazine motor or drive fault
• Heavy tool in magazine causing overload
• Magazine position sensor not detecting pocket
• Mechanical jam in magazine

Diagnosis:

1. Check magazine motor and gearbox for binding — rotate magazine manually if possible.
2. Check magazine position proximity switch gap and alignment.
3. Inspect all tool pockets for tools that are not properly loaded (hanging loose, oversize diameter).

Alarm 2108: ATC Door Switch Error

Alarm text: ATC DOOR SWITCH ERROR

Trigger: ATC enclosure door is not confirmed in the required position for tool change.

Causes:

• ATC door not fully closed
• ATC door proximity switch failed
• Pneumatic door actuator (if equipped) not moving door to position

Reset: Verify ATC door is physically closed. Check switch alignment.

Alarm 2110: ATC Interlock Alarm

Alarm text: ATC INTERLOCK ALARM

Trigger: One or more preconditions for ATC operation are not satisfied.

Common interlocks that block ATC:

• Spindle not at orientation (M19 not confirmed)
• Coolant not off
• Axis not at tool change position
• Chuck in wrong state

Diagnosis: Check the PMC ladder for the specific interlock signal that is not satisfied. The ATC interlock ladder net is typically one of the more complex sections — look for the output coil that enables M06 and trace back to all its input conditions.

Alarm 2127: Changer Arm Position Check Alarm

Alarm text: CHANGER ARM POSITION CHECK ALARM

Trigger: ATC arm is not at its confirmed home position when expected.

Causes:

• ATC arm home proximity switch failed
• Arm physically not returned to home (previous tool change incomplete)
• Pneumatic actuator for arm not extending/retracting

Diagnosis:

1. Check arm home switch status in PMC.
2. Manually return arm to home position if it is accessible (machine in emergency stop).
3. Check air supply to ATC arm actuators — typical requirement is 6–7 bar.

Coolant and Lubrication Faults

Alarm 2020: Coolant/Lube Pump Motor Overload

Alarm text: COOLANT & LUB. PUMP MOTOR OVERLOAD OR Q11 FOR SERVO TURRET, CHIP CONVEYOR AND BAR FEEDER OVERLOAD IS DETECTED.

Trigger: Thermal overload on coolant pump, lubrication pump, chip conveyor motor, or bar feeder motor has tripped.

Diagnosis:

1. Locate thermal relay for the specific motor — check which relay is tripped.
2. Coolant pump: check for coolant tank running dry (low fluid causes pump cavitation and overload) or blocked coolant nozzle/filter.
3. Chip conveyor: check for chip jam. Remove chip conveyor guard and manually clear chips if jammed.
4. Lubrication: check for lube reservoir empty or lube pump seized.

Alarm 2050: Lubrication Pressure Down / Oil Level Low

Alarm text: LUB. PRESSURE IS DOWN OR LUBRICATION OIL LEVEL IS LOW, CHECK LUB. UNIT AND REPLENISH THE OIL.

Trigger: Lubrication unit pressure switch or low-level switch has activated.

Causes:

• Lubrication oil reservoir below minimum level (most common)
• Lube pump failure
• Blocked lube filter
• Pressure switch fault

Fix: Check lube unit reservoir sight glass. If low, refill with correct oil (typically ISO VG46 or 68 — check machine specification). Press lube unit manual prime button to pre-fill lines, then reset alarm.

Alarm 2069: Coolant Filter Change Alarm

Alarm text: COOLANT FILTER CHANGE ALARM

Trigger: Coolant filter restriction sensor or scheduled maintenance counter has activated.

Fix: Replace or clean coolant filter element. Reset filter change counter in machine maintenance menu.

Alarm 2074: Cooljet Low Pressure or Filter Block

Alarm text: COOLJET LOW PRESSURE OR FILTER BLOCK ALARM

Trigger: High-pressure through-spindle coolant (cooljet) system pressure is below minimum or filter is blocked.

Causes:

• Through-spindle coolant filter clogged — replace filter element
• Cooljet pump failure
• Air in cooljet system

Fix: Replace high-pressure coolant filter. Prime pump by running coolant with spindle stopped.

Spindle Faults

Alarm 2022: Spindle Orientation Confirm Not Detected

Alarm text: SPINDLE ORIENTATION CONFIRM IS NOT DETECTED WITHIN 10SEC.

Trigger: After an M19 spindle orientation command, the orientation confirmation signal has not been received within 10 seconds.

Causes:

• Spindle orientation position sensor failure
• Spindle drive not configured for orientation (parameter issue)
• Mechanical issue preventing spindle from reaching orientation angle

Diagnosis:

1. Check spindle drive orientation parameter settings on the alpha amplifier.
2. Check the spindle one-revolution sensor (encoder-based orientation uses spindle encoder; position-coder orientation uses a separate sensor).
3. On Fanuc 21i/31i: verify parameter 4077 (orientation stop angle) and parameter 4073 (orientation command direction).

Alarm 2101: Spindle Tool Unclamp Alarm

Alarm text: SPINDLE TOOL UNCLAMP ALARM

Trigger: After commanding tool unclamp (drawbar release), the tool unclamp confirmation switch has not fired.

Causes:

• Drawbar actuator (pneumatic or mechanical) not releasing tool
• Tool unclamp proximity switch failed or misaligned
• Air pressure insufficient for drawbar release

Diagnosis:

1. Check air pressure at drawbar actuator — typically requires 6–7 bar minimum.
2. Verify unclamp switch position — it should detect the drawbar release piston movement.
3. Manually trigger unclamp while listening for actuator operation.

Fanuc Servo Alarms (4xx, 5xx)

These alarms come from the Fanuc servo software layer, not the Doosan PMC.

SV401: Soft Overtravel (Plus Direction)

SV402: Soft Overtravel (Minus Direction)

Trigger: Axis position has exceeded the soft limit set in Fanuc parameters.

Causes:

• Work offset or fixture offset is incorrect, causing the program to command a position beyond the machine envelope
• Soft limit parameters (1320/1321) are set incorrectly

Fix:

1. Jog axis away from limit.
2. Verify work offsets (G54–G59) are set correctly.
3. Check parameter 1320 (positive soft limit) and 1321 (negative soft limit) if the machine’s envelope seems wrong.

SV410: Servo Error Excess (Position Error Too Large)

Trigger: The difference between commanded position and actual feedback position has exceeded the tolerance parameter (typically parameter 1828 — position error limit).

Causes:

• Axis mechanical overload (cutting too aggressively, axis jammed)
• Servo motor encoder failure
• Servo drive fault
• Ballscrew or servo motor coupling failure (backlash or broken coupling causes position error to accumulate)

Diagnosis:

1. Note which axis tripped the alarm.
2. Jog the axis slowly and feel for rough or jerky motion — indicates mechanical issue.
3. Check encoder cable connection at motor and at servo amplifier.
4. If alarm trips in cut: reduce cutting depth and feedrate.

SV414: Servo Overload

Trigger: Servo motor thermal load has exceeded limit.

Causes:

• Axis mechanically overloaded (cutting force too high)
• Axis preload too tight (ballscrew or guideway issue)
• Ambient temperature too high in servo cabinet

Diagnosis:

1. Allow servo motor to cool.
2. Manually jog axis and check for smooth, consistent resistance — rough or tight spots indicate ballscrew or guideway issue.
3. Check servo cabinet ventilation and cooling fans.

SP740: Spindle Alarm (Spindle Overload)

Trigger: Spindle motor current has exceeded the overload threshold.

Causes:

• Cutting forces too high — reduce depth of cut or feedrate
• Tool wear — dull tool requires more cutting force
• Spindle bearing failure
• Incorrect tool/material combination

Fanuc System Alarms (9xx)

900: ROM Parity Error

910: SRAM Parity Error

920: Servo Alarm (Emergency)

930: CPU Error

These are serious system-level alarms indicating hardware failure of the Fanuc control.

Alarm 900/910 (memory errors): Indicate corrupted memory in the Fanuc CNC board. Symptoms include parameter loss, program loss, or strange machine behavior.

• Check battery on the Fanuc control (lithium battery, typically replaced every 3–5 years)
• If battery is low or dead, memory may have been corrupted during power loss

Alarm 930 (CPU error): Indicates the main CPU on the Fanuc control has faulted.

• Usually caused by EMI (electromagnetic interference), loose board connector, or failing Fanuc main board
• Reseat Fanuc boards; check grounding connections

Reset Procedures

Standard Alarm Reset

1. Address the alarm condition (fix mechanical, electrical, or program issue).
2. Press RESET on the Fanuc MDI panel.
3. If the alarm does not clear: the condition is still active. Check MESSAGE screen for remaining active alarms.
4. For E-stop or servo alarms: power cycle may be required after reset.

Power Cycle Procedure

For alarms requiring power cycle (servo amplifier faults, 9xx system alarms):

1. Press E-stop button (if not already pressed).
2. Turn main power key switch to OFF.
3. Wait 30 seconds for DC link capacitors to discharge.
4. Turn power key to ON.
5. Machine will perform startup self-test — reference return (homing) is required after power cycle.

Reference Return After Power Cycle

After any power cycle, Doosan machines require axes to return to reference point:

1. Select REF mode on mode selector.
2. Jog each axis in the positive direction until the reference return completes.
3. Order: typically Z → X → Y → other axes.
4. Until reference return is complete, Alarm 2031 (PLEASE MANUAL REF. POINT RETURN) will be active.

Replacement Parts

Where to Buy Replacement Parts

Find replacement parts for Doosan CNC machines on Amazon:

• Doosan CNC Machine Parts
• Fanuc CNC Control Battery Replacement
• CNC Lubrication Pump & Distributor Block