Question
I have a RainMaster 18E irrigation controller.  There are a couple of issues and we are trying to determine if it's the controller or another issue.  First, station 16 opens and runs while any of the other 18 stations are running.  When one of the other stations finishes it's run time the valve on station 16 will close.  Checked the wiring, checked the solenoid, checked the diaphragm and all appear to be good for valve 16.  Even replaced the diaphragm and solenoid just to be sure they were not the issue on valve 16.  Finally disconnected the quick connect at the controller for line 16 and now station 16 no longer runs.  Tried to get a new quick connect although have been having difficulty locating one for the model.  Can't figure out though if it's the controller or wiring between the controller and the valve.  The other issue that indicates the controller itself may be the problem is that randomly various stations will light up on the controller panel indicating that they are running, however they are not.  It could be station 4 for a few days and then station 11 tomorrow.  My best guess is that the controller is in need of replacement, but before we spend $$$ on a new 20 station controller we want to be sure it's the issue and we are not throwing money down the drain.

Answer
Hey Holly, this is what I would suggest. With the field wire disconnected from station #16. Turn on one of the valves, lets just say valve #1. Now with a volt ohm meter, see if you are getting a reading on the terminal #16. If you are, then you have an internal  problem, and the controller needs to be repaired. If you are not getting a reading, then you probably have a wire problem. Before you replace the controller, I see you are in Arizona. Take the controller to any of the Sprinkler World of Arizona locations, and they can repair it for you. Phoenix store # 602-954-9022. Good luck and have a great day.