The brake coils are wired in parallel, period. Your 1.6 ohm reading possibly indicates that only axle is connected. I have totally (every single wire replaced) rewired 2 trailers of the OP's vintage with dramatic results. Increasing the wire gauge never hurts either. I usually run 12 gauge with one wire from each axle to the connection with the 7 lead umbilical cord. If OP still has the original wire inside the axle tube it's time to replace it with new wire tie wrapped to the outside of the tube to prevent future shorts.
