Ok. Here is another update. I was WAY off with what the problem is. There is a large part of the back yard that is not functioning. I thought because Valve 5 was not working it was the valve that powers the sprinklers that don't work. I was wrong. Valve 5 definitely doesn't work, but I have finally come to the conclusion that it probably worked at one time but is now obsolete. I consulted with my gardner and he showed me more valves that are up in the hill buried underground (6 of them). These are the valves that bring water to the area that currently is not working. Confirmed this by opening the bleed screws. Since the area that I thought was controlled by one valve is actually controlled by 6 valves and none of those valves are working, I concluded that this has to be a wiring problem. Since all 6 zones are not working at the same time, I'm pretty sure it can't be 6 solenoids going bad at one time. I took apart my controller to gain access to the station screw terminals. Based on some research I did, I figured out how to test the controller, but I don't really know exactly what the test results mean. I was told to activate a station and put one lead on the common and the other on the station screw terminal to get a voltage reading. After the reading is confirmed, with the zone still active, put the lead on the other zones to make sure the voltage reading on those zones is zero. So, I activated zone 1 and got a normal voltage reading from zone 1. But with zone 1 still active I placed the lead on station screw 2 and also got a voltage reading. I repeated for zone 3, etc. and got the same result - voltage reading on other zones, when zone 1 is active. What does this mean??
The thing that threw me off about this whole process is that these zones stopped working right after I did work on the pvc pipes. But it appears to be entirely unrelated.