Starting a dual-mode's engine?

Ok, so now four railroads in the U.S. operate dual-mode locomotives, Amtrak, NJT, MNRR, and LIRR. I've seen videos on YouTube of the startup procedure for "normal" diesel locomotives and it's pretty involved. However reading some of the posts here, it sounds like turning on the engines of these dual-modes is basically just the flick of a switch, like if the third rail units gap out and they need to turn the diesel on to get across. Do they run in some kind of very low idle while under electric? Or could "normal" locomotives be setup to just flick a switch?

starting a P32acdm is just holding a toggle switch in on position for 30 seconds.
it will take engine a minute or two till it spools up to power a train.

DutchRailnut wrote:starting a P32acdm is just holding a toggle switch in on position for 30 seconds.
it will take engine a minute or two till it spools up to power a train.

So it is possible then to have the diesel engine idling for a minute or two (warming up), but still have the locomotive running in e-mode? I've observed several outbound P32AC-DMs depart 125th without hearing the prime mover rev up but still maintain great pick up speed.

http://www.youtube.com/watch?v=nRZVnPSbOOw" onclick="window.open(this.href);return false;

correct,inbound we leave diesel running while running in E-mode, till cab car is entering platform in GCT , outbound most engineers will start engine leaving park ave tunnel and switching over just before the Harlem river bridge(cp-4).

On Amtrak the engine is started almost immediately after departing Penn Station where the open cut between 9th and 10th Avenue was (now completely covered) and letting it idle to warm up while still in e-mode until leaving the empire tunnel, since the 3rd rail ends not far past the portal.