Extended Idle???

I have a 94 XJ 4.0 4x4, it used to be a Sheriffs K-9 vehicle. I know the extended idle button just to the left of the steering wheel is there because law enforcement usual sit at idle for long periods. Besides turning on the AC, fan and bumping up the idle, just curious does anyone know if does anything else? In addition, if it will affect my planed engine swap?

Actually, my understanding of the ext. idle was that it was used for boosting electrical power, things like jumpstarting people's cars (in fact a cop once did this for me--I'd totally killed my battery & first he tried to jump it without high idle, tried a couple more things & finally had to turn on the ext. idle). Off-roaders tend to use them for powering winches, OBA, etc. It seems like a nice feature to have. Also, those police pkg XJs came with better wiring than stock street vehicles.

I don't know that it will affect your engine swap. If you're keeping your existing wiring harness it should work the same way it did before. But if you have to swap in a new harness to go with the engine, then there might be some difference, I don't know for certain.