Although many fixes to automatic sprinkler systems are relatively easy DIY projects, finding the system components sometimes seems challenging. Valves control the water flow, and the solenoids in the valve systems occasionally need replacing. When the system needs repair, finding the valves in the ground takes a bit of trial and error, but you can narrow your search.
Turn on your sprinkler system and watch which sprinkler heads rise first. The heads closest to the valves tend to appear first, which helps you restrict your search to a small area of your yard. Your kids can help be other sets of eyes, running to mark the spots of the first sprinkler heads they spy.
Check the ground for flat plastic or metal covers, usually rectangular. Because these are flush with the ground, they might be difficult to see until you're right on top of them. Look near the main water line first -- most valves are located close to the main line -- and branch out in a circular pattern to find the covered valve boxes.
Review a blueprint of the sprinkler system. If the system installer didn't provide you with a copy, call to see if the installer has one still on file. Check with your local permit department; in some areas, you must file a blueprint with the local government before installing the system. Requesting a copy might require you to pay a small fee.
Use a solenoid activator, also called a chatterer, to locate the valves. The activator causes the solenoids to start chattering, or turning on and off quickly to make a clicking sound. Walk around the area where you think the valves are located and listen for the chatter. Some sprinkler supply and home improvement stores rent the activators, which saves you money over buying one.