Testing a String of Serially Wired LEDs

Let’s say one of the strings of lights is not working correctly—how do you troubleshoot it? This FAQ is for series-wired LEDs.

Tools required:

  • OJ-606 short (3 pcs)

Installed Switches:

  • AL-WS-DR1, AL-WS-Bath: Turn the switch on, set to minimum—this will supply about 20 mA for testing.
  • AL-WS-DR2W, DR2C, DR2 with firmware 23 or later: Enter Test Mode to supply 7 mA for testing.

Entering Test Mode:

  • Break the circuit by disconnecting one LED in the string that is not working.
  • Turn the switch off.
  • Wait 6 seconds.
  • Turn the switch on.
  • Wait 6 seconds—the switch outputs 7 mA on the LED output(s) with no complete circuit.

Setting up the Test:

  • Let’s say you have 4 LEDs in a string.
  • We are only testing series wiring today.
  • Disconnect 3 LEDs and bypass them:
    • For tunable white: connect the male/female OJ-606 together.
    • For fixed color: connect the OJ-606 short in place of the LED.
  • Leave just one connected so the loop has only one active LED.

Testing the LEDs:

  • Turn the LEDs off, wait 6 seconds, then turn them back on.
  • The string(s) being tested should pulse for the calibration sequence.
  • At the end of calibration, the connected LED should dim from off to full brightness. If not:
    • Remove the LED, turn the light off (6 seconds), on (6 seconds), then off.
    • Replace that LED, mark it, and install a fresh LED. Restart testing.
    • If all LEDs fail, there is likely a bad wire.
  • Repeat by connecting 2 LEDs, then 3, then 4, returning to the first step each time you add another LED.

Testing the Wiring (requires a voltmeter and a screwdriver):

  • Remove the switch from the wall.
  • Use a lever nut to short the wires that go up to the LEDs in the ceiling.
  • Go to the first LED and measure the loop resistance; it should be less than 1 ohm. If it is greater, find the break.