during installation of NEW FLD Detector it started to show error Excitation Motor didn't find its position then gives error Excitation motor has failed and last error it still showing up is Exciation endcoder index failed to calculate so what do you th

Hello Mohsen,

it's very odd that a brand new detector would display this error.  What is the model number?  That error means it cannot read the EX motpr position for the EX diffraction grating.

This error is usually shown for a motor which was used over some time period [worn out] and will require replacement.  Suggest you log a service call with Agilent as it should be under warranty.