ESP-LXD 2-Wire Decoder Control System Installation & Troubleshooting Guide
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Break / open circuit in the 2-wire path cable
You will notice one or more stations are not running even though they are programmed to
operate. If the system is using flow sensing, you will receive a low (zero) flow alarm for each
disconnected decoder station.
- Use the Test All Stations to check which stations are operating
Controller diagnostics
- Turn dial to Test All Stations / Check System; Select 2-Wire Diagnostics
- Select Decoder Test - The results will indicate that one of more decoders have an Open Circuit
and you will be prompted to Check Wiring; Go the location of the decoder that are not
responding and check wire splices
2-Wire Path diagnostics
- Check your as-built drawing. If you notice that all the decoders that are not responding are
in a single leg of the 2-wire path, the open circuit exists between the last working decoder
and the first non-working decoder. Check the splices at that location first. Also look for signs
of recent construction/digging between the working and non-working decoders.
- Turn the controller dial to 2-Wire Diagnostics; Select Short Finding; Turn Short Finding Mode
On. Use a Clamp Meter to measure the Amp Draw of the 2-wire path cable conductors at
the last working decoder and the first non-working decoder. Note any discrepancies in the
readings. You must know the number and type of each decoder downstream to know what
the mA reading up should be reading (see Calculating the total system mA draw section for
more information).
Short circuit (red and black wires crossed) of the 2-wire path cable
The controller alarm light will be illuminated and the alarm will inform you the controller has
switched to Short Finding Mode. You must fix the short circuit before the controller will switch
back to normal irrigation mode.
2-Wire Path diagnostics
- Disconnect each 2-wire path cable one at a time from the controller ESPLXD-M50 Decoder
Module until the controller exits Short Finding Mode. Reconnect that 2-wire path cable, and
if the Short Finding Mode returns you know the short is on that leg of the 2-wire path.
- Refer to the as-built to see the location of the 2-wire path. Walk the route of the 2-wire path
cable and check for signs of recent construction/digging.
- Find a decoder location about half-way down the 2-wire path cable. Disconnect the splices.
See if the controller is still in Short Finding Mode. If the Short Finding Mode has cleared, the
problem is downstream of this location. If the controller is still in Short Finding Mode, the
problem is between this location and the controller. Keep disconnecting segments of the
2-wire path until you isolate the problem.
