I had a mechanic switch my automatic transmission to a standard on my 03 Jetta TDI wagon. Everything works fine except the cruise control. He did not know how to hook it up. VW dealer service wouldn't touch it, but charged $100. There are some loose plugs dangling from the auto wiring. It may not be possible to get it working, but if anyone can tell me how, I will give them $100.
If it's factory cruise it may just be a question of coding . Diesel ECM's need to be coded for the cruise to work. The ECM is probably still coded for an auto, and might affect it's function.
If it's not factory cruise, go to an aftermarket installation shop.
Its the round plug right? I really don't think that you can make your CC. work with that harness. You could switch engine harness's for a manual trans. one and then it would work.
Diesel ECM's need to be coded for the cruise to work.
... and I think the Ross-Tech website has the required VCDS steps.