Ok bit of a weird one now on a 03 Doblò jtd
Whilst driving today I had to break a bit sharpish and to my surprise the internal overhead light came on
This is the first time this has happened
While breaking normally this doesn’t happen but only when I break hard
I have tested hard breaking today and without fail the light comes on
I really would like your input on this please :bang:

There should be no reason why the internal light is on any circuit near the rear lamps, so we can probably rule out a short circuit or bad earth on the brake lights.

If this is the interior light that comes on when a door opens, you might have a door that needs adjusting a little tighter on its catch, or it might have a duff switch. Most door switches these days are incorporated into the doorlocks, but some are still at the doorshut as a mechanical switch. If the Doblo has any of these, might be a good idea to check.
A hinged door wiring is usually fixed, and flexes near a hinge, and wiring can chafe here, and the harsher braking could be connecting two wires.
Sliding doors make wiring to them more challenging, often using brass/copper contacts at the doorshuts. These may need cleaning, or checking the sprung part is still working ok, as the harsher braking could be losing the contact.

Good luck with that, some time fiddling needed.