If your Diff Lock light is coming on from stepping on the brake, you must have either some crossed wires or one heck of a short somewhere.

Especially with that Cruise Control Vacumn Pump melted like that. I would be examining all the wiring under the hood before I went any further.

How is the vacumn pump removed. I want to replace all my vacumn tubing and would like to unbolt or whatever you do to get the pump out from where it is mounted.