Hi all, came across this little circuit that you can add to the interior light to delay the off time once the door has been shut.
I modified it to suit my Multipla (which has two 10W lamps in the fitting), made it and am really pleased with it.
It gives that extra second or two to find seatbelt etc rather than plunging you into darkness at this time of year
As it stands, I think it stays on for about 4 seconds but if you lower the value of R3 in the attached picture, that will lengthen the on time, eg 3.3K ohms instead of 4.7K ohms.
I wouldn't recommend a massive on time though, as the main transistor, T1 has to dissipate the heat all the time the lamp is on once the door's shut. That's why I kept mine shorter.
As for fitting, one connection goes to the negative side of the lamps (the Grey wire) and the other to the ground (the Black wire) although I soldered mine onto the actual busbars of the domelight rather than the connector block as I found that easier to do, rather than in situ.
Hope it's of use to someone here though. Enjoy

Thanks for that. My 2004 round-nose has a time delay on it already - stays on for about 5-10 seconds. It would be nice to have it stay on longer!