Hp Designjet T2500 error 09.4:10

[Robertv2]

I get this error on boot up Hp Designjet T2500 error 09.4:10

[D Hook]

Here's a link to an error explantion:  https://www.meicomputer.com/services/designjet-error-codes/?model=T2500&errorCode=9:04:10

It indicates one of the lamps in the scanner assembly is beginning to fail.  This is the error code explanation from the service manual:

09.04:10
Problem Description: CIS C Element is failing
Corrective action:

1. Replace CIS C Element CIS Element (MFP only) on page 538
2. Clean the scanner of dust and dirt and perform the Scanner Calibration Calibrate the
Scanner on page 234
3. If the system error persists, upgrade with last firmware version. For more Information
about see Appendix B: Emergency firmware upgrade with USB flash drive on page 121
4. Replace Scanner Controller board.

You can try shutting down the machine from the front on/off button.  The open the top of the scanner and look at the lights.  You'll see them marked by each light A, B. C, D and E.  The "C element" refers to the third light, which may be failing.  Leaving the cover open, turn on the printer and watch what the lights do.  If the C light fails to come on, that's the one that needs replacing.  The lights should then all come on either red or blue and begin flashing slowly.  The C element may flash, along with the other four but it doesn't mean it's good.  

I have this same machine, but it's the T2300 model.  Same scanner but the printer is a little different.  I've been having the same problem with mine and have replaced one of the lights already but the error then moved to a different light so I'm working on trying to determine if it's the lights or the Scanner Controller board.  Neither the lights or the control board are cheap so determining which one to replace is difficult.  You can try replacing just the light first and see if that solves the problem.  It's not difficult to do but having a service manual is very helpful.  Just google " Designjet T2500 Service Manual" and download it.  (Be very careful removing the glass plate because that a very expensive fix if broken.)  You might try reseating the cable to that light first to see if that helps.

The service manual will explain how to update the firmware also, which you might want to try before anything else.