R53 Most liked posts in thread: Pass. Heated Mirror not working

Orientation isn't necessary for a resistive heating element (it will work if you plug it in either way). Even if the wires aren't marked, certainly one of them is positive and the other is negative.

Here's the wiring diagram. The circuit is very simple:
https://www.newtis.info/tisv2/a/en/r53-cooper-s-hat/wiring-functional-info/body/seat-mirror-function/exterior-mirror-passenger-s-side/mirror-heating-passenger-s-side/qeJvirf

If it isn't working, the connection to power or ground is broken somewhere. A good place to check is at the connector by the door hinge. It will tell you if the signal is good up to that point.
The connector is X256 in the wiring diagram. Pin 1 is power; pin 19 is ground.
https://www.newtis.info/tisv2/a/en/r53-cooper-s-hat/UvKyIgm
https://www.newtis.info/tisv2/a/en/r53-cooper-s-hat/1VnXmGZsdR

 

Even a humble homemade test light can show you if you have power at those connections.

I wonder if it is a broken wire in the loom that goes from the car to the door. Lots of flexing going on there.

Good luck with your search. Maybe it is a Lucas mirror.

 

Door mirror in working condition, but does not need to be perfect. I will repaint and replace glass if needed. Lever needs to function properly.

I know some of you have some fox junkyards. My garage is starting to look like one also.

 

When you have the mirror off make sure the two wire connections are good.

 

A wiring diagram, your trusty voltmeter, and time. Wiring / power problems can sometimes be easy but most times very humbling. Good luck with your quest.