I read your post and started to wonder why my current department vehicles don’t have the up-idle system that my last department had so I asked. When they purchase their fleet from the manufacture the department has the option to order the up-idle system which is now built into the alternators and communicates with the engines computer. When it senses a drop in power it revs the engine for a higher output. Now the yard that maintains my department’s vehicles also does the fire department. They said that the pull brake system that is used in the emergency vehicles is a little different. On the newer units when the break is pulled and the break light comes on it tells the computer to increase the revs. On older units it had a second cable going to the throttle. They said that the up-idle system was more problematic than it was worth and that it also caused more alternator failures and overheating of the electrical system do to less air flow to the alternator. My current department is using high output alternators from
http://www.nationsautoelectric.com/highoutput.html and it seems to work out better with less failures of the electrical system. This site does carry them for the Toyota. If you do want an up-idle system they are only available for the CVPI, Explorer and Expeditions as far as my maintaince yard knows, and can be found
http://www.americanarmature.com/police.htm.
I will say this about high output alternators, that in three years with the same vehicle and averaging 250+ miles a day and the engine only being turned off maybe twice in a 12 hour shift, I have not had an alternator fail yet. In my last department with the up-idle system I lost an alternator once a year and it always happened in the summer on highway patrol in the middle of nowhere.
Hope this helps. You might also might want to ask your maintanice yard.