2006 Hemi p0740 Code
 

I have had this truck for about 3 years and put about 40000 kilometres on it, but ever since I’ve owned it, it has displayed that code, I have reset it and it comes back on at highway speeds. Everything works fine and I’ve never had any trouble with the transmission. Looking for anyone that’s had similar problems and what you did to fix it?

Might be wiring, might be the solenoid. Test the wiring, see what ya get.

I don't have a manual for your year truck..... Might wanna get one. That are indispensable for working on these.... Wiring diagrams, parts locations, connector pin-outs. Everything you would ever want to know about your truck.