How and when the slides function is specific to the class and model. I had a Class C and the engine had to be off to extend and retract the slide. I now have a Super C and the engine has to be running to extend and retract the slide.
You can try going to the Thor Owners Site and downloading the schematics for your specific coach to see if you can find the interlock to bypass it.
https://www.thormotorcoach.com/owners
Thor Forums
