Question
A problem occurs when zone 2 comes on and stays on while the other zones come on and proceed through the normal sequences of time.  The systems shuts off as required.  The water pressure is reduced in the subsequent zones after zone 2 remains on.  Why does zone 2 stay on?

Answer
Hi Les
Check the AC on port 2 while watering other zone, should be 0 Volts, if you get 24Volt or a little bit more the port is damaged, if you have any free port move the the wire from port 2 to the free one.
If the problem is not at the controller, probably you have a faulty selenoid on valve 2, replace it, if the problem continues check the valve and replace the diaphragm if necessary.

Good luck
Guillermo