Genie Intellicode IS Series, it had a previous owner.
Sensors mounted in garage but not electrically connected (door closed by holding down button).
Attached the sensors to the opener. The indication lights were completely off, nothing... so decided to get new sensors and re-do the wiring.
Next, bought new Genie Safe-T-Beam Replacement Kit sensors and did new wiring.
For the wires, I took the same wire position from each sensor and twisted them together at the very end where connected to the openers electrical ports #3 and #4 (Figure 3-5 B in Genie manual link above).
When connected, one sensor will blink red - the other sensor completely off.
Sensor 1: Red LED light: 2 blinks, pause (repeat)
Sensor 2 Green LED Light: OFF
Wire to sensor missing or bad
However, if I connect only Sensor 2 to the openers ports (and not Sensor 1) the green light will come on.
So this tells me the wiring to that sensor is working.
Why would the sensors not work when connected in pair?
Any help is appreciated.