Karel,
You are in the correct Forum for Damon RV questions.
There are 4 general "parts" to the Ultra-Level system:
Jacks, Pump and Valve Assembly, Control Panel (on the dashboard), and the Control Module - or the "brain."
The "brain" should be mounted on the ceiling of one of your pass-through storage bins - closest to the center of the RV (left/right and front/rear).
It may be covered by a black plastic shell and is at the end of a wire harness.
The main power has a "breaker" not a fuse in the large power cable in-line to the pump. The main brain has a fuse...but are in different locations by model (unknown to me).
Hope that helps.
Best luck