I did the research, and now you don't have to. It's super simple to do.
Parts list:
KA24DE Cruise pump (1990-? 240SX)
KA24DE Cruise Diaphragm (1990-? 240SX)
Original connector from your 200sx cruise control (Cut it off)
Connector for KA24DE Cruise pump. (Cut this off too)
Picture of supplies:
Here is what you need to know!
I used some old trailer wiring I had laying around. It's about 4 feet long. Which ended up being slightly too long. So I recommend measuring before making this.
Then Tape it up. It's all done!
Now go to the car, and put the cruise pump and cruise diaphragm up by the windshield wiper motor. It's a pretty snug fit, but the pump will go in there. You don't need to put it there, you can mount it wherever you deem good enough.
Mount the diaphragm somewhere on the passsenger side too.
Connect the throttle cable. connect plugs.
Boom! Cruise using your stock equipment.
You NEED to make sure you keep the vacuum switch from the original motor. It doesn't affect the cruise other than saying "There's a vacuum here". So you could get away with just grounding it's connector out. But it's not that hard to ground out the actual switch.
This may or may not work for SR20DET motors, and CA18DET motors. I do not have access to those motors so I don't know if the throttle cables are the same between them all.
Picture of it all said and done
Happy highway cruising!
i feel like im going to do this, just because i can