Probably a bad CLC, you should be able to unplug the group comm on the bad car so you can power it up without taking down the group to troubleshoot. The bottom 2 plugs on CLC are comm, left, LCC10 is group, right, LCC9 is car. Without power and plugs off you should read 460-48 ohms from pin 2 to pin 4 land at least a Meg ohm from 3 to 1. On both LCC9 and LCC10