How to use a Multimeter to Determine if You Have a Bad Controller, Valve, or a Wiring Problem

Multimeters are handy for testing many kinds of wiring or electrical problems. Considering their versatility they are amazingly affordable. While they vary in complexity from basic to how-many-functions-did-you-say-it-had levels, we only need the basic here.

The most important thing to know if you have never read one: read the instructions. Two or three times. Make sure you understand the symbols and connections. There are few things as interesting as trying to test a 110AC wall outlet when your meter is set for low voltage DC. You’ll know you messed up.

Your problem: your valve won’t come on. And we don’t know why. There are really three electrical reasons it might not: bad controller, bad wires, bad solenoid. We always start with the simplest test first. [...]