1761

Common Causes

• Faulty EC input signals from the gear-range confirmation switches: I/O check NO.29 INPUT bit 8 (iMA241, M241) and bit 9 (iMA242, M242)
• Gear match confirmation limit switch out of adjustment, so it does not actuate at the true gear position
• Gear shift mechanism not completing the change, leaving the switches between positions

Troubleshooting Steps

1. 1Read the code number shown with the alarm: code 1 = Gear range command and gear position limit switch states disagree during M-tool spindle rotation
2. 2Stop the M-tool spindle before investigating; do not reach into the gear area while the live tool drive can rotate.
3. 3Open the I/O check screen and monitor NO.29 INPUT bit 8 (iMA241) and bit 9 (iMA242) while commanding each M-tool gear range; confirm the bit pattern changes to match the commanded range.
4. 4If a bit does not change, inspect the gear match confirmation limit switch for that range — check its actuator/dog alignment and adjust the switch position so it actuates positively at the engaged gear.
5. 5Check the switch connectors and cable back to the EC input for looseness, oil contamination, or damage before condemning the switch itself.
6. 6If the inputs read correctly but the alarm returns, record the alarm number, code and object and contact Okuma service.