4 of the 6 zone won't work

My sprinker unit is 13 yrs old, which has a 6 zone sprinker system. Zone 1,2,3,4 won't work. Zone 5 and 6 works fine.

Issue:
The first 4zones won't come on. The wiring all look OK. When I run the unit on manual mode and turn on the 1st. zone, I noticed that there is voltage (approx 10-15 v) on zone 2,3,4. However, zone 5 and 6 have "0" volts. So there is bleeding of voltage on zone 1,2,3,4 which ever zone I make it active.

When I go to manual mode and set zone 5, the voltage on this zone is 20 V and all the other zone show zero voltage. Ditto for zone 6 also. Which I guess should be the way it should work.

What is going on on zone 1,2,3,4. What should I do to fix this issue. I thought the control box is fried and just replaced a brand new Rain Bird system. Please help .... ....appreciate your help in advance.

MP

First, I would not rely on any voltage meaurements taken with all the wiring connected. I would disconnect all wires at the controller, and repeat your test measurements. My first suspect would be an open neutral ( probably white) wire involving one or more of those 4 valves. Such an open can cause you to get confusing voltage measurements like you did. You will just need to disconnect things and make some contiuity measurements on all the wires.

are you sure all your solenoids are good?