My N/S electric mirror decided to stop going up & down but is still heats up & moves in & out.!
So I know that it's not a fuse & the power supply is ok, next is either the switch it self or the motor in the mirror.
Any easy DIY way to find out or test which is failed?

Just to add, there has been no knocks to either part!

Cheers
Iggy

 

The only way is to take a known live and touch it to each connector on the mirror in turn, watching what, if anything, it does.
Make sure you don't touch it to the earth wire though, LOL.

 

Mmmm ok thanks!