Vintage Cars: rearwindow heating, market switch, check connections

Question
QUESTION: I am the owner of a W115/8. The rearwindow heating doesn't work.
Do you have the electric shedule for me, so I can fix it.
Greeting from the Netherlands.

ANSWER: what year, ?
typically check - fuse, and fuse block both sides with Ohm meter
check switch
check connections on rear window connection, usually in the corner.
Also if the window is delaminating the continuity will be broken in the thin wires and it will not work


---------- FOLLOW-UP ----------

QUESTION: 1972 W115 200D.
No rearwindow heating.
I must new wires en switch install.
Gr Jan

ANSWER: are you saying you want to add rear window defrost?
I am not sure what you are asking

---------- FOLLOW-UP ----------

QUESTION: My car was build in 1972, without rearwindow heating.
A previous owner put rearwindow heating in but there are no more wires and there is no switch.
I want to install new wires and a switch but I don't know how to do this.
I'm looking for a schedule how to connect the wires and switch.

Thank you, Jan Hofman, Netherlands.

Answer
ah
you would need to run wireing from  fuse box, from  a keyed 20A fuse ( comes on only when key is on) and run to after market switch that then powers the rear window element.  
It is really pretty easy if the window element is there.  Basic power pull off fuse box ( a red fuse) and then to switch that has ground and power output to window element You can buy a simple on off switch
hope this helps