Gen 3 not watering, but says active

I installed a Gen 3 a week ago. I have two groups of valves, one on each side of the house, connected with two different sets of wires. Everything was working fine yesterday when I was running all of the zones to test the watering schedule. Today, one group of valves stopped working. I tried switching the common wires, but that didn’t help. The unit indicates it is watering, but it is not and I can’t hear the valve solenoids activate when I turn on any of the zones in that group.

I’m guessing this has something to do with the wiring, but I’m not sure how to get started troubleshooting it. There are five wires plus the common wire connected to the valves. The affected valves are, of course, on the other side of the house, so I’m really hoping it’s not a break in the middle of the cable buried somewhere under the house. The common cable connection at the valves does look a little suspect, but looks like a good connection (not weather-proofed, however). Should I start by just connecting the common wire to one valve and go from there?

Any suggestions on how to figure this out?

Thanks!

I would guess a wiring issue as well and as you said, the ground on the valve box end would be my first suspect. Since it is not waterproofed, it might not really be giving you a good connection. That is really a common place for loosing a connection even coming loose.

Do you happen to have a multimeter? If so, the following might help: