I'm having issues once in awhile so I did the whole turn ignition on while holding trip button and some numbers came up on odometer such as. First set that flashed was S127 then .285 and finally c447 finally Hr3635. I know that the last number is hours but what are the rest?

 

http://wiki.dieseltruckresource.com/wiki/Computer_codes

Check out that link.

The soft codes are when something happens, but it's not serious enough to set a regular code or CEL.

To check the hard codes, turn the key on/off three times (sometimes it's four times) and the P codes will display. Don't press the trip button.

 

If I remember correctly, turning the key on while holding the trip button will result in the instrument cluster being put into self test mode. It will not display engine codes this way. Madhat gave the procedure for displaying engine codes.

 

https://www.dieseltruckresource.com/...s-t224833.html