Unknown line

I have an existing sprinkler system and recently replaced all the old valves due to age. One of the stations does not come on at all with no water running through the line. I disconnected the line from the valve and verified the valve is in good working order. I suspect the line has been pinched or capped off. Since it was a pre-existing system I don't know where the line actually goes.

Is there anyway to trace the line so I can figure out if I even need the line?

I don't think there's a very good way to trace PVC pipe. Since it is non metallic, metal detectors will not work. About the only way I know is to dig out around the sprinkler and see which way the pipe heads. Then use logic (which may or may not work) and assume the pipe would have been laid with 90* angles. Then dig some test holes to try to find the pipe. That's probably too much work just to be able to use the existing pipe, so you might be better off just to lay a new line and forget about the old one.

First, it is poly pipe so I can't assume 90* angles. Second,I don't know where the first sprinkler head on the line is located or if there is one. I am not sure if the landscaper cut through a line and capped or if I even need the line.

Thanks for the ideas, doesn't look like this is going to be easy either way.

Is there water going to this zone valve?
Is there water leaving this zone valve?

Is there a section of grass that is not getting watered?
If you have 100% coverage, then you don't have a problem.
If you have a zone that is dry, then you need to poke around with a screwdriver to try to find the sprinkler heads and isolate the blockage.

Yes, there is water going to the valve. Yes, there is water leaving the valve if I disconnect the the sprinkler line. No, there is no water leaving the valve when the line is connected to the sprinklers leading me to think the line is capped somewhere.

All the grass appears to be getting watered. I was thinking it might be an overlap condition due to the different types of heads because there is one area which is a little dry.

I just wanted to confirm the line was dead so I wouldn't worry about it. I was hoping there was some trick to finding the capped end or unused heads, but it doesn not appear to be the case.

Thanks for the ideas.