You may have a timer relay on your irrigation system that you plug into its slot before the system starts working. Such plug-in timer relays may at times fail to work as expected when they are being installed for the first time. This article discusses some of the solutions that you can try in case a new relay timer fails to work once you plug it into its slot.
Re-examine the Number Orientation
Many manufacturers of timer relays usually provide diagrammatic illustrations of how the timers should be installed into the socket. However, the diagram provided is usually a mirror image (a reversed image) of how that timer should be installed. This orientation may confuse some inexperienced people who may inadvertently reverse the order in which the timer relay should be installed. So the first thing that you should do in case the new plug-in timer relay doesn't work is to check the orientation of the pin numbers. Make sure that each pin on the timer relay has been inserted into a corresponding number within the socket into which that timer relay has to be installed. This reorientation is likely to correct any errors that you had made.
Check the Voltage Source
Some timer relays have voltage outputs that are not connected to the voltage input side of the mechanism. This design enables the relay to be used to provide output power that differs from the magnitude of the input power. It is therefore possible that your plug-in timer relay is not working because the relay contacts on the output side aren't connected to the input power. The solution to this problem is to read the installation manual so that you learn how those relay contacts can also be connected to the input power source. The system will then work well.
Check Input Polarity
Many plug-in timer relays use direct current (DC) instead of alternating current (AC). Your device may therefore not be functioning upon installation because you may have got the polarity wrong. Confirm that the positive terminal on the device has been plugged into the positive terminal in the socket of the timer relay. The negative terminal should also be checked for correct fitting.
It may be better to contact a professional for help in case you implement the suggestions above but the timer relay still fails to work. That expert will examine the entire set up and make the necessary changes so that your system starts working again.