I have a Dakota Digital Odyesy Speedo installed in a 1991 740 Turbo and the cruise control doesn't work. I suspect the shop that installed it has a wrong connection somewhere. Does anyone have any experience with these installations.
Just to backtrack the shop sent a complete instrument cluster to Dakota Digital and they installed the speedo in the housing. The unity itself has worked flawlessly for 10 years, just no cruise control.

Are you trying to use the Volvo cruise control the car came with? I have the wiring diagram for my 1989 740 and if your 1991 is the same it shows a terminal "E" on the back of the speedometer labelled "Cruise Control Digital Output". It is a single male spade connecting to a Yellow wire.

If your Dakota speedometer lacks this, there is no speed signal to your cruise control's electronic module. If the Yellow wire is connected to the Dakota unit, possibly the output signal is not compatible with the Volvo cruise module.

If you have a Dakota Digital cruise assembly, try contacting Dakota Digital's tech help line or email.
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Son's XC70, daughter's XC60, my 83 244DL, 89 745 (Chev LT-1 V8), and XC60. Also '77 MGB with Chev V6, and four old motorcycles. Long gone: 1981 244, 1994 940,1998 S90 and 2010XC60 (totalled by hitting 500lb elk)

Thank you, I will look into this. I had a wiring diagram for the car with the cruise control wiring and cannot find it.