My system has space for 18 stations, but I have only 15. Remember the difference between a program and a station.
What is the brand of the control box. I will try to explain this with my Rainbird.
I have space for programs A - B - C and D. But I only use A and B. So just because you have 18 stations and 4 programs, that doesn't mean all have sprinkler heads or valves.
First, set the control to SINGLE STATION, and THE BOX SHOULD DISPLAY STATION ONE then press ON. Locate where that station is and mark it on a sheet of paper. Then go back to the control box and press OFF. Then press NEXT and on, locate that area where your sprinklers are on, and then go back and turn that one OFF. Just keep going through this until you see all your sprinkler locations and have written them down.
To the right of the box panel is a vertical area when you can set the programs to A - B - C or D. When you are running through the OFF/ON drill above, look to see whick letter that vertical panel is set to. Remember, you have say, 8 sprinklers for A, can have 2 set for B and 5 set for C. Each program operates like it was the only one.
For example, I have 15 stations set for Program A, 2 stations for program B and none for C and D. So station 1 runs once a cycle on program A, 2 runs once - through station 5. The for station 7, it runs once on program A and once on Program B (once on the 2 am cycle and once on the 5 pm cycle)
Be sure you day and time are set correctly for the currrent time.
So there are stations (your actual sprinklers) and Programs (usually up to 4 programs - that A B C D area to the right). Then there are start times for each.
Perhaps what has happened is the power went off and it set to start at 12am and end at 12 am and so it just keeps running.
Go through Program A and all it's stations. Check the time each one shows. Go through each program and all that program's stations. Write it all down.
Then look in the display box at the top and you will see the watering days. The dial can also be moved to 'watering days" and will display the days your current system is set for. By pressing NEXT you can change the watering days to every day, odd days, even days or do a individual setting all your own.
The only thing my unit will not do it run the programs (A and B) on different days. I have not figured out a way to do that.
So I have programs A and B in my tablet. I could use A B C and D but don't
I have 18 possible stations. For program A, I run 15 and for program B I run stations 6 and 11 only. I run each station 18 minutes 4 times a week for Program A and for stations 6 and 11 they run 5 minutes on Program A and 5 minutes on Program B.
Once you figure out the difference between programs (A B C or D - a set of stations) and stations (actual sprinklers) and watering days and start times and station times (the later is how long the sprinkler actually runs) you can locate the problem.
Hope that helps.