Diagnosing Toro EL-6+ Controller Zone Wiring Issues

Toro EL-6+ Runs Zones 1 & 4 Together; Zones 2 & 3 Inactive

When a Toro EL-6+ activates two zones simultaneously and ignores others, the fault lies either in the controller or the field wiring. A voltage test at the controller’s terminal strip isolates the problem.

Voltage Test Procedure

1. Remove all zone wires (1‑4) and the common (C) from the terminal strip. Label each wire for reconnection.
2. Turn the controller on and activate station 1.
3. With a volt/ohm meter, place the negative lead on the C terminal and the positive lead on terminal 1. A reading of 22–26 VAC confirms proper output.
4. Check terminals 2, 3, 4 while station 1 is active—they should read 0 VAC. Any voltage on inactive terminals indicates a controller fault.
5. Repeat for stations 2, 3, 4. Only the active station’s terminal should show voltage.

If the controller passes all tests, the issue is in the field wiring or valve solenoids. Inspect for crossed wires, damaged insulation, or faulty solenoids.