There are TWO different "High Idle" programs--
"Elevated idle" is a factory program that can be set on/off through the steering wheel controls or other. It ONLY will work if the temperature is below freezing and will turn off if you apply the brake or put in gear. The idle is only one speed -1000 RPM-??
The other idle is "High Idle" -- is normally a PTO option where there are three different speeds. It is set through the cruise controls, and will work at any temperature. The option can be added to most vehicles by sending power to the ECM- terminal.
If wired correctly, it will turn off with the brake or when into gear.
Chevy 04.5 LLY, 2X, shell, XDR, MikeL Heavy duty up-grade, 6spd, TransGo, deep pan, de-badged, 65 Gallon replacement Aero tank, LBZ-mp, Kennedy pump, shimmed, Pre-fuel filter, tow mirrors, BU cam, gauges, GPS, Sirius, bags, custom grille, fender vents, HD trans cooler- Curt front hitch, footwell lights, load lights, Studs, head gaskets.--- Jerry