I tried starting my system last weekend and the controller seemed to be working fine but nothing happened. After studying posts here I realized that my wiring was probably cut when I had a generator installed a few months ago. I figured the path from the valves to the controller should be pretty much a straight line so I started digging, and then dug some more and then some more!
Feeling dejected I thought I might need to rent a wire detecter but then I recalled reading how to find a break in an underground dog fence. I reviewed the approach - google underground dog fence break - and sure enough it worked to connect my dog fence transmitter to my irrigation wire and use an am radio tuned to 600 to follow the wires by listening to the beeps. When the beeps stopped I figured I'd found my break. Sure enough, 2 minutes of digging I found the break within inches of where it was predicted to be! (and not near the generator but rather by a stump I'd had ground down.)
At first I figured I'd need to buy more cable to splice it back together but I realized I was lucky it occurred near a right-angle bend that I could short-cut in a way that gave me enough extra cable to wire it all back together!
Thanks to all here for their advice and now I'll go learn how to adjust the heads.