Fanuc OT Servo Alarm 401,424

Have a z-axis servo alarm that I need help troubleshooting. I have gone through the steps in the manual to try to figure this out but want another opinion before I break down and call in the troops!

1. Checked the plugs at the motor in question, and they appear free of coolant and chips (as clean as can be expected for a 12 yr old machine).
2. When power is disconnected from servo motor and machine is booted up, no alarms are present.
3. Tried swapping the wires at the control box (servo control) with those from the x-axis, and the alarms pop up for the x-axis now.
4. Checked continuity through all 4 wires of the cable with both ends disconnected from servo controller, and servo motor. Good contact.
5. Checked ohm reading across motor pins (ground to leg, leg to leg). No ohms ground to leg, about 1.5 leg to leg.

Is it a motor, drive, or cable problem (or something else)?

Thanks!

If 4x4 alarms are shown you should check diagnostic para. 720~723 for details, each bit in these 700 diagnostic shows the reason for the 400 alarm for each axis.
The servo amp servo manual give details of tuning and trouble shooting the alarm codes.
Al.

Unfortunately, I am without the servo manual. Diagnostic parameter 721 (z-axis) reads HCAL (abnormal current).

it seems servo drive has a problem

Yep, Drive, motor, cable or screw. I replaced a drive last week with the same alarm. I thought to check the cable...it was ok, then the motor...ok...found the ball screw ejected a few balls and put it in a bind. Replaced the screw and drive. Now all is good. I could have easily zapped another drive if I didnt take a few extra steps. Sometimes electrical parts go but it is well worth the time to check a few things before "throwing parts" at a problem.

Situation resolved! Took out motor and took apart the female power plug on the motor. Had some corrosion on the wires that was causing a short. Ordered the plug from Fanuc for $11.00, soldered it up and was back in business. Sure beats sending the motor in for the $165 "evaluation", and the inevitable purchase of a rebuilt motor from Fanuc for $2000.00!