Wired Scale Systems with Erratic or Incorrect Weight Readings

In most cases erratic readings come from a faulty cable. Wiggle and shake the cable on the channel that is in question. Most of the time, cable damage or internal shorts are within 12” of the end connector. If the channel readings change, get better, or go to 4 dashes, then the cable is most likely defective.
Try a different scale pad from another channel to test the channel in question. If the problem stays on the channel it is possibly the cable. If the problem moves with the pad, then it is likely a load cell issue.
If the calibration has been tampered with it could also cause erratic or incorrect readings.
When zeroing the system make sure there is not any weight on the pads.
If the pads are in levelers or in some kind of a rig, make sure nothing is interfering with the top pad ½.