The brown wire from the VSS on the back of the speedo produces a squarewave signal that the painless controller says it will support so it should work together.

 

Now to figure out a cool spot to mount it. It actually has a chip that records ambient temperature, so if you return it, they check it. Pretty smart. If the chip shows over 265, warranty is null and void.
Of course, cooler is better for electronics.

 

The DD controller has way more capability that just turning a fan on/off. And works with your existing gauge/sending unit.

The PAC-2750 was designed for the ultimate in flexibility and to be a simple add-on in any application using an electric fan. Included is a 70amp relay, enough for even the most power hungry of cooling fans. Fully programmable, the PAC-2750 will work with your existing water temp gauge, operating from the temperature sending unit already installed. A dedicated sending unit can be installed for applications without a water temp gauge. OBD II compatible vehicles can obtain the engine temperature from the ECM with the use of a BIM-01-2 (or previous BIM-01-1), purchased separately.

When used in conjunction with BIM-compatible Dakota Digital instrumentation or a BIM-01-2, a single cable transfers speed and temperature data to the PAC-2750 allowing the fan to be shut off at an adjustable highway speed!

The PAC-2750 features fully programmable “fan on” and “fan off” temperatures to suit any application or personal preferences. The PAC-2750 has the capability to leave the electric fan operating after the engine has been shut down for a user adjustable time. The PAC-2750 offers a full digital LED readout for displaying temperature readings and maintaining simple installation. A second relay is required for dual fan or two speed fan operation.