The step is operated by an ex Toyota Coaster electric door closer and folds against the side of the truck when not in use. The weight of the person on it is supported by stainless steel ropes at either end.
 
An ignition type switch requires a key to be inserted and turned before the step can be raised or lowered from the outside. The step can also be raised from inside using another two-way switch but doesn't need to be protected from misuse so no key is required.
Step goes up ...

Step goes down ...