Accelerometer signal feedback has large noise frequency even when there is no motion or hydraulic power on (Figure 1).
Figure 1 – Noise on acceleration feedback signal
Check the cable connector. Some cables have resistors in the connectors that can cause this. If the cable was made by MTS there should be a part or material number on a white label near one end of the cable. The cable drawing can be requested with this part number to check to see if the correct cable is being use or if there is a resistor in the cable.