Steps have 2 hot leads and possibly 3
One is to battery or constant power (after disconnect switch) and this one carries operating current.
The second one goes to ign power and is a sense lead that tells controller key is on.
This overrides the manual operator switch so steps come up when engine is started.
That operator switch may also be a voltage source but too early to remember...Others will comment on it though.
Get a copy of the manual for your step to confirm what power needs are then confirm where connected.
It could be plugged into wrong place.
Tony & Lori
1989 Country Coach Savannah SE