easiest way to tell probably is to pull the back seat and see if you can spot the vacuum pump. It may sound like a lot of work but it'll take you two seconds. If memory serves me there are two pul tabs towards either the back or the front. but they are red so they are hard to miss. just pull the bottom of the seat out and look on the passanger side there should be something in black squishy foam with lots of hoses going to and fro. that would be your central locking pump.
your fuse box should I swear its 9-12 somewhere in there is the fuse for this but it says ontop of the fuse box which one is for which, but the vacuum pump's pretty easy to look for really.
I have an 85 and it had central locks, but don't know if it was standard issue.
1985 190e 2.3