I have a 1993 2500 6.5. I have been trying to find out just what does the computer on a 1993 6.5 do? Is it necessary? Is it just for the tranny shifting? Thanks Gordon.

No indication of transmission type in your sig -

if it is automatic, that is a TCM - Transmission Control Module

if it is NV4500 equiv, could be emissions - EGR, EFE, etc.

I suspect you have a 2500hd and thus a F motor. The injection pump is mech and lift pump is powered of OPS. If you have a 4l80e you only have a TCM. I swapped to a nv4500 so I no longer use my TCM. I am not sure how the glow plugs are controlled, but those I have set-up as manual as well. There is a VSSM box behind the glove box to that deals I think with the speedo, abs, and cruise. All three are seperate of the TCM though becuase all three still workwith the TCM removed.

Sorry about that I do have an auto trans 4L80e. It is 2500hd type F. Gordon.