Multi Plex Lighting System - problem

Explain better. You have 2 keypads that have the Master Light switch. You were not clear on your response. Do BOTH Master pads NOT control the lights or 1 does and the other does NOT? They send a channel signal to a master control board. Each button response is designated a frequency channel. So, Since the lights go OFF and then come back ON, there can be 2 possibilities. 1. The Keypad is defective internally and the ON side continues to send the signal and WILL override the other keypad which as you will do, disconnect the defective keypad and test. If the other Keypad operates the system correctly, you have a defective keypad. 2. IF NOT, then the master control board is bad. Doug