I moved into a house that was a foreclosure but has an irrigation system. There was no one around to show me how to set everything up. I know where the control box is and have read the instructions well enough (I believe) to test the heads but nothing comes out. I have gone out to the box outside in the lawn where the valves are and they all seem to be open. I assume the problem is that there is some master water shut off valve to the system that I have not found. I'd rather not spend $100 to have someone come out to just turn a valve if I can help it. Any thoughts? It is a rainbird system if that helps but I don't feel that is relevant in this case.
First thing to check: is there (or was there) a well? If your sprinkler system is attached to a well, then this is the first thing to check. Make sure it's on and operating correctly.
If it's not attached to a well, then it's just a matter of tracing the pipes, possibly from each end. Locate the main shutoff in the house and any lines running to unknown locations, particularly back outside. Make sure all valves are open. Then from outside, trace the line running back into the house and check if there are any access panels in the path that could be hiding a valve.
Finally, just an obvious check, check your breakers and make sure the system doesn't have a rain switch that has been activated.
A couple of ideas:
As another poster mentioned I am wondering if there is water pressure in the lines already.
You can try this if you think there is water pressure in the line: - In the valve that is in the yard there is usually a solenoid on top that the power comes into. Most will allow you to manually turn on the zone by turning the solenoid, or have a small handle besides the whole shutoff switch. See this http://www.rainbird.com/documents/diy/ValveInstallTips.pdf page 7 for a diagram.
For finding a secondary off for the irrigation, I have had them in the basement just before heading to the outside line. I have also had them installed outside above ground in the warmer climates.
Let us know what part of the country/planet you live in. There are norms that vary from region to region.