it was an X10 coupler/repeater. It has been removed. I am still getting intermittent operation.
For instance, I have a 2334 8 button keypad hooked up on one side of the house which works OK. I have installed another 2334 on the other side of the house and it won't link. the led blinks green, but does not sync and finally it turns red. There are two switches on that side of the house that do work.
Thanks