How to Troubleshoot the Sprinkler Controllers on a Lawn Master LM12

Pull the white wire from the "Common" terminal on the LM12 to reset the connection if the timer has power but the valves don't turn on when activated. The common wire might be compromised. Slide the common, or white, wire back into the terminal.

Pull the lid off the valve manifold box and find the white common wire that connects to all valves. The white wire should be bundled together with wires from the valves and sealed with a watertight splice connector. Unscrew the splice connector from the bundle and confirm that all the wires have been stripped about a half inch and are touching.

Open the LM12 front cover and disconnect the 9-volt battery from the bottom if you are unable to program the timer or if the timer shows a blank display. Unplug the LM12 from the power source and allow the unit to rest for one minute. Reconnect a new battery and plug the unit back in.

Flip the "Program" switch, which is on the left side of the front panel, to the desired program letter if the timer misses a cycle. Twist the LM12 control knob, on the front panel, to "Auto Start Times" to verify that the desired start time is set. If the correct start time hasn't been set, use the "+" and "-" buttons to adjust it accordingly.

Twist the LM12 control knob to "Days to Water" to confirm that the day in question is selected as a watering day if a cycle is missed. If the desired watering day isn't activated, press the "Next" button until it's selected and press the "+" button to activate it. Press the "-" button to deactivate a day as a watering day.

Twist the LM12 control knob to "Watering Duration" to observe set watering times if the sprinklers fail to turn off. The watering duration time might be set too high. To decrease the watering duration time, press the "-" button until the desired number of minutes is reached. Do this for each program to confirm the schedules don't overlap for one zone.

Twist the dial to "Auto" if the sprinklers fail to turn on when scheduled. The schedule isn't put into effect until the LM12 dial is set to "Auto."