Sprinkler System Troubleshooting

Sprinkler system troubleshooting requires a systematic approach. This is how to troubleshoot a sprinkler system if you try to turn it on and nothing works.

First, check the obvious. On a city water system, the troubleshooting of the irrigation system would go like this:

1. Is the water on? The backflow device open? Separate meter open? If you know where a sprinkler valve is located, open it manually to see if there is water in the sprinkler system. Is there a pipe break so large that there is no water left to pressurize the sprinkler?

2. Is there power to the controller? Open the controller and check the "24 volt" power connection terminals with a volt meter. You should have a minimum of 26 volts. If you do not, check the breaker if it is an outside sprinkler timer or the 120 volt plug-in outlet if it is a plug-in controller. If you have 120 volt power but no "24 volt" power, the likely problem is the 120/24 step down transformer. You can replace this without replacing the entire sprinkler timer.

Turn on zone one and check to make sure that 26 volts of power is going to the sprinkler terminals by placing one volt meter probe on the common terminal and the other on the zone one terminal.

3. So, lets say you have water and power. Now we move on to the field wiring. Did it rain? Disconnect the rain sensor and place the field common directly on the controller common terminal.
Sometimes in the course of sprinkler system troubleshooting I'll see where some lazy idiot wired the rain shut-off to the common in the ground instead of inside the controller where it belongs. In that case, hire a private detective to hunt down the installer and break his knees to keep him out of the industry.
With the rain sensor out of the loop, using an ohm meter place one probe on the common wire and the other on zone one. It should read between 20 - 60 ohms. If you have a master valve on your city water system, check that first. The terminal will be labeled MV or PS for pump start.
If all the zones read far above 60 ohms, you have a common wire problem. The first place to look is where the field wires enter the ground. Sometimes you will find wire slices in this area.
The next place to look is at the first valve electrically downstream from the controller. In this situation you may need a wire finder.

Hopefully these tips will help you with your sprinkler system troubleshooting.