W203 stepper motor - battery disconnect?
 

I'm half way into taking the dashboard out of a 2003 w203 to get at a clicking stepper motor.
Typically its not the easy one (that can be got with just the bottom half of the dashboard out) - its one in the top of the heater box.
I've been working with the battery connected but the next stage is to remove the steering wheel, instrument binacle and then the top half of the dashboard.
The Mercedes Workshop Information System (WIS) states I need to attach a quiescent current device (????!!!) - why?
If I just disconnect the battery what will happen ?
Secondly does one really have to remove the steering wheel - it seems to be one hell of a job in itself.
If its too big a job can anyone suggest an independent that might take on the job at the half dismantled stage in the south east of england -I'm near Guildford in Surrey,
Julian
Any advice appreciated.