I have an old Sears Craftsman (Liftmaster OEM) garage door operator with a wall-mounted receiver, connected to the operator by three wires (red, white, and black). The original receiver can open the door and also operate the unit’s light fixture. Shorting the black to white operates the door, shorting the black to red closes a relay and causes the light to go on as long as the black and red are closed.
I set DIP switches 1 & 2 to ON, and ran the original black and white wires to the COM and N/O terminals for relay 1. I ran two jumpers from those to the POWER terminals to supply power to the 202U.
Then I ran another jumper from one of the POWER terminals to the N/O terminal for relay 2, and connected the original red wire to the COM on relay 2.
I cleared the codes and set up each remote for button A to operate relay 1. So far, so good. The remotes both open and close the door correctly.
Then I cleared the codes for relay 2 and configured both remotes for button 2 to operate relay 2. Unfortunately, what happened was that button B now operates the garage door (relay one) and button A does nothing.
I repeated these steps 5 or six times and the results were the same. I cannot get relay 2 to operate the light at all.
I thought that it might possibly be a polarity issue, so I reversed the black and white wires on the POWER terminals, so that the red & white wires would be shorted for relay two. When I reprogrammed the remotes the result was the same; I could get button A to reliably operate the door, but when I attempted to use learning button 2 to program relay 2 to use button B, it would instead program button B to operate the door.
Have you ever seen this behavior before? Could it be a defect in the learning circuit? It seems that both learning buttons operate on the relay 1 circuit.
Other than the “oops” moment when programming relay 2, and the changing of the DIP switches to demonstrate the various operating modes of the relays, I don’t see how this process is any different from the ones in the printed materials. So yes, I have followed that procedure.
What’s interesting is that I can’t re-program either relay without a power cycle reset. I can program each relay once. If I press the “learn” buttons again, they don’t respond. So maybe it is a power problem. I guess I can test that theory by clearing all codes, and then programming relay 2 to operate the lights first, before I program relay 1, and see what happens.