I'm assuming you've looked through all of the menu options, I know it can be done on a Doblo 2013 as I did it on mine - not sure if the software load on the 500/L might be different - there may be a difference due to the Doblo being classed as a 'Professional' (ie commercial) model.
Just checked on my 500L (also 2013) and I can't find any settings on there either, possible that there might be something you can turn on/off in MES but I haven't plugged into it yet on mine so I can't be sure.
Yea, I had bulbs in the wife's auld 2012 Punto. That you couldn't switch on. Yes a set of clear 5w indicator type bulbs in the corner of the headlights. I originally though they were marker lights or dunno. I thought they were indicating bulbs. But they're in the front bumper