What is normal resistance reading for 5er brakes?

Sounds pretty close, but I'm not sure what the exact reading would be. Does your brake controller show a good connection or give you any error message?

One way to tell if the brake is working at each wheel is to hold a compass right next to the hub of each wheel while someone applies the brakes. The compass will deflect.

If your brake controller looks OK, they may just need adjusting. Most trailers, as they come from the factory, are not self adjusting. They adjust like a regular star wheel adjustment.