Land Rover Repair: Differential Lock Lite Displayed, differential lock, electrical issues

Question
I can not get my Disco II out of park.  The service engine light has been on for a couple days but I thought it was due to a loose gas cap.  Anyway now the differential lock light is and it will not shift out of park.  Any suggestions.

Answer
With several seemingly un-related error messages and problems, one of the first things to check is the battery condition.  LR's are not happy with low voltage, which confuses the ECU's.
If the dif-lock light is on and it is NOT locked, I think you have electrical issues.