Home Improvement → Re: My four out of nine stations won't come on

The two pictures of the wiring at the rainbird controller are good. Even so we can't see it because of the conduit, it appears that the valves are wired with a single 10 conductor cable.

That cable must first go to valves #5 through #9 before going to valves #1 through #4. The white wire marked COM is the one that doesn't have continuity between the 5-9 set and the 1-4 set of valves.

Unless you already know (or can guess from the layout of the valves what the likely cable route is) you will have to take a picture like the last one of all 9 valves.

However even that picture isn't useful because I can't tell with certainty how many wires are attached to each of those two wirenuts and what their colors are. You may want to carefully bent the wires to show the underside of the wirenuts and where necessary clean up the wires to show their colors.

I think each valve has one black wire connected to color wire (ex: yellow for 1st station) while the white wire connected to COM wire. These wires then run to the controller via the cable. Therefore, logically only one COM wire shared to all stations. If this COM shorted then it should short other stations as well, right ? BTW, this spinkler system was built by sometime ago by the pro and it had been working until recently and I didn't alter the wires connection. I also tried to open wire at the valve of 1st station and measured again the power of station#2 through #4 and still see the power come on the same time. Is there anything need to be programmed at the controller for the COM wire if you know ?

Correct, there is only one COM (common) wire that needs to connect to one side of each valve solenoid.

That COM wire isn't shorted anywhere, it is disconnected/interrupted (which is the opposite of a short circuit).

Based on all the information that you have provided so far there is absolutely nothing wrong with:
- the rainbird controller
- the wires at the controller end
- the cable from the controller to the first valve (which is definitely not one of the valves #1 through #4)

There is no amount of reprogramming the controller that can fix a disconnected wire.

Unfortunately for you, the problem is either inside one of the 9 valve covers (loose splice) or buried in the ground (damaged cable between valves).

If the COM wire is white at the rainbird controller and black at the valves it must be spliced somewhere (probably at one of the valves).
Edit: it seems I misread what you said about the wire colors. The color of the two wires from the solenoid to the wirenuts isn't really important since it is AC anyway (so no polarity issues). What matters are the colors of the wires in the cable that goes from the controller to all the valves. There may be more than one cable which makes it important to look for splices.

I finally got it fixed but I had to hire a expert to trace out the open wire. They used the locator to identify the open COM node between valve#05 and valve#04. The confusion was that the COM wire run from valve#9,8,7,6,5,4,3,2,1 in that order but the controller connected to valve#1,2,3,4,5,6,7,8,9 in that order. That was why the first 4 valves (1 through 4) stop working because the COM wire open at valve#5. First 4 valves worked when the COM wire of valve#05 was reconnected.

Anyway, thanks for your help and I hope that this lesson-learned can be applied for someone else if they run into the same issue.
One more thing, it costs a lot ($$$) when you call a service that you're not sure what is wrong with the system (they will think something to charge you as even the issue is just a simple fix).