I'll guess again... the add on 3rd brake lamp kits would come with a logic module. If both brake lamps came on it would come on also. It would not come on with power from only 1 side. That so it doesn't blink with a turn signal. That was the purpose of the logic module. It should not be capable of interrupting one or both brake lamps though. Half assed cut and taped wires at install certainly could.
