for lack of a better word i use the term "ping" and forms of "ping" for performing a test. connect the TDR to the common and the valve wire, ping the pair and record the measurement. do this with all of the valves, once you have all of the results you'll know where each valve is in a physical order and what the valve assignment is at the controller. if there is a compromise you may be reading a "length" distance, that should put you pretty close. if the valves happen to be assigned for operation, regardless to their physical placement you may find that the common is compromised and the valves are actually the last valves or they're on a branch and the splice is corrupt. when i look at a group of valves not functioning regardless of their location i eliminate the common, i don't dismiss it. without a TDR, short to earth measurements rule.