Initial install, wires not marked. Easy what to determine what's what?

I had an old 1993 RainBird system with 12 zones. The system has a custom 24 pin connector, and then a “breakout” connector for a freeze/rain sensor. I’ve managed to figure out most of the zones, but can’t figure out where the common and master are. I know my system has several pumps, but I don’t know where they are (I can hear them–they’re VERY LOUD.)

Is there an easy way to determine what’s what with the wires? I’ve cut the wires behind the connector and shoved them in the unit where I thought they’d go. The unit will not water, however.

@dlleon Can you take a picture of the old system and sent to

Trust me, we’ve seen our fair share of wiring :wink:

Thanks and have a great day!


Don’t hesitate to post the before/after pics up here, so others might be able to see what you did.

Down here, the common is usually white. Can’t help wit the master.