Rear wiper, window demister, and a multimeter - help!

[CMF_Martos]

Howdy! 1999 K11, bought a few months ago. Rear demister has never worked. Rear wiper has stopped working. I've just bought a multimeter am wondering how to proceed.
Okay, the rear demister has never worked, but the switch on the dash lights up and I've replaced the fuse in the fusebox inside the car. With the rear wiper, it used to never return to the same point on the window when I switched it off, just stopped where it was. Now it has stopped altogether. Swapped my mate's rear wiper motor over with mine and mine worked okay on his (including parking itself properly) but his working motor did not move on mine. Replaced the fuse but nothing. What do I need to do with multimeter to check where the faults in the wiring (presumably) might be?

 

[CMF_1300cc]

if i send u a copy of the rear wiper wiring diagram, would that help?
im guessing it the relay switch

 

[CMF_frank2]

its usually a break in the wires where they pass through/into the tailgate martos, i would set the meter to 12vdc (usually 0 to 20v) and check that there is a feed, and working earth to the connectors on the tailgate

frank

 

[CMF_Martos]

Back at this again! Here's the bit from the Haynes manual. Two sets of wiring diagrams in the book. Top left is for 2000-2003, bottom right for 1993-1999. Mine is 1999 but I've got the fusible linkbox from one and the passenger fusebox from the others. This renders the wiring diagrams in the book useless. Not that it makes too much difference as I can't even work out how the wires get from the back of the car to the front! How simple is it to just run a new wire to the wiper?