the problem with the harness is the older Fiesta ST and the newer Fiesta ST having different plug for the harness. The Recaro seat/older Fiesta ST has a 16 pin connector and the Newer/base Fiesta ST has a smaller 8 pin connector. Other than that, everything else within the seat plugs in as it would.
I happen to have an extra seat harness that plugs directly into the base model 8 pin connector to solve the incompatibility problem.