First thing to do is notice the display on the Irritrol RD600 series Irrigation timer; the top row of the display will have a small number that indicates which station is turned on.
If the water is on, and you do not see a number on the top row, then it’s usually not a timer problem. Look at the other DIY Troubleshooting section for information on “what to do when valves stay on when they’re not supposed to.” Also try following the DIY Troubleshooting instructions to timer to reset it to its factory defaults. This clears out all the programs and leaves a default program which is set for everyday of the week starting time of 7 a.m., every station for 10 minutes. if you don’t want that schedule simply change it.
If you do see a number on the top row then the irrigation timer has programming set to turn it on. To figure out what program is causing it, change the dial to point to that station number. The display will show you the letter “A, B or C : xx” where xx is the remaining irrigation run time.
The letter indicates the schedule that is running. now put the bottom center switch on set programs and the schedule switch to the schedule letter you saw above, and check all the programming. the program should indicate a start time that you’re not expecting simply change the programming or stop that schedule by setting the star times to off or all the run times to zero/off.
Pay careful attention to the AM/PM settings it’s easy to get those mixed up and you’ll find that your timer runs 12 hours earlier or later than you expected to.
Also keep in mind that the start time indicates when the stations start watering and they go consecutively in order, so if you have each watering for an hour that schedule will not finish till 6 hours later.