From the master car, type DHNF for front, DHNR for rear. There will be a 1 or a 0 next to each node. If that node has a 0 you probably need to replace it. When you enter the DHNF it may tell you you have a blown fuse at that HN. There is a software glitch where this happens on power up. Says there is a blown fuse but there isn’t. Cycling power doesn’t fix it but pushing the reset button on that node does. Long term fix is replace the HN or update the firmware on all the HNs.