I'm not sure if #1 is the key car. The weird part is that the hall lights stay lit as if a hall call is registered but no cars show up to answer the call. If you place a car call on one of the cars with the tool it will respond to the car call. Car #1 is the only one that locks up the group when it is powered on. If the power is off on car #1 the group works fine. This problem is intermittent, it only happens every other time the car is powered up or every third time. Every time it fails the status shows "Blocked" on the tool. I have not found any thing that shows what blocked means.