No, you aren't crazy. The Auxiliary Idle Controller (AIC) was originally offered by Ford for various diesel trucks and vans. The AIC ties into the factory harness for the ECM and allowed the user to control the idle while the vehicle was stationary to run lights, pumps, and whatever else you can think of that would be run by the engine or transmission mounted PTO. The AIC can also monitor the charge of the batteries and when in Battery Charge Protection mode it will ramp the idle up to a max of 2400 RPM in order for the alternator(s) to keep the batteries in the truck charged. Ambulances use these for running all of their emergency lights and other equipment onboard. F series trucks with hydraulic dump bodies that run off the transmission PTO use the high idle function. It can also be used to prevent what is called "wet stacking" which is where the truck idles for a long period of time and actually accumulates unburned fuel in the cylinders which then washes down the cylinder walls removing the oil from the cylinders and causing accelerated engine wear. A lot of guys just use an aftermarket switch and mount it in the their truck in a convenient spot and it is very easy and inexpensive to do. I chose to buy the AIC kit from my local dealership so that I could have the full set up. This is much more expensive to the tune of $700
, but I like the fact I have both the Battery Charge Function and the PTO control with a digital tach display so I know exactly what is going on....and it looks cool at night too!!!
Here is the section of the Ford Fleet Vehicles website where there is a reference to part numbers for the AIC as well as wiring diagrams for the harness.
https://www.fleet.ford.com/truckbbas/non-html/2003/bb_pdf/196-198.pdf
Hope this helps.
Patrick
