I have a Rainbird sprinkler system which is 10 years old. When I tested it at the beginning of the season all was well. But then a problem arose when I noticed two of my stations (#1 & #2) were not receiving sufficient pressure. I should note I have 9 stations of which two are for flower beds. During my investigation of the problem I noticed station #5 was also on (albeit at low pressure also) when #1 or #2 were on, but when I turned on other stations it went off. When #5 was on by itself, it worked with correct pressure. If the system is off for several days, the entire system works normally but the problem raises it head again the next time it is used. OK, I thought it was a wiring issue, so....
- Checked voltage and verified only one station was receiving power at the main controller. PASSED
- Checked function of #5's valve by applying power on and off. PASSED
- Checked voltage of #5's power when wire was disconnected and #1 or #2 was on...no voltage. PASSED
-NOW the weird....I disconnected #5 when #1 was on after I verified #5 and #1 were both on even though only #1 was getting power, result was #5 turned off. BUT, no voltage was being sent to that wire from the controller. (???????)
- OK I thought maybe the controller was to blame so I changed #5's wire to a spare #10 station and I got the same exact problem as before. Controller PASSED
I would change the #5 valve (even though it seems to work) but I cannot locate the station.
I thought I was a pretty good trouble shooter, but I can't make heads or tails on this one.

Couple of other tidbits...

- These two valve stations are on two levels(my yard is on a hill), #5 is lower

- I don't have a gang valve setup, each valve has it's own box. I don't know where any of these valve are (I know where the rest are.)