There are a few ways that you can tell if your heat pump thermostat wiring is faulty. If you notice that your heat pump turns on and off frequently, that could be the sign of a problem. This activity would be a more abrupt and frequent on-and-off than the normal heat regulating pattern used by a properly working thermostat. Another way to tell if your thermostat is faulty is if your home experiences wide and frequent temperature fluctuations. If you look at your six thermostat wires and everything seems properly connected and in good shape, then check your fuses to see if you may have a fuse out that is preventing your thermostat wiring from doing its job.