State of Iowa legal code?

I need to find the exact section of the Iowa code of traffic enforcement that states the requirements of the officer and/or his department to keep up regular maintenance on their speed detection devices. I need this very badly so any help would be appreciated. I have nothing against law enforcement its just that I absolutely cant afford to have this ticket show up on my record so if any nice officers out there could throw me a bone and give me a hand I would be very happy.