Rear demist and heated mirror fault

[fesprior]

Hi have a ph 2 172 and heated rear screen and mirrors are not working!!

There is 12v across the fuse, the UCH clicks when I press the switch and the dashboard light comes on. Have no voltage at the rear screen. Have unplugged connector that sits in footwell behind sill cover and have reconnected. Still nothing. Checked the wiring in the mirrors and connector in rear screen. This is driving me nuts. Back of the brain thinking a failing UCH BUT no other gremlins. Car has done 61K and (bar this) has been without fault.

I ought to add that I also checked the earth below the left rear light and the nit seems tight.

Any help much appreciated.

Thanks
F

 

[bmh.01]

If its closing the relay I doubt theres anything wrong with the UCH, tried another relay?

 

[fesprior]

Hi

Good question. It is the UCH is clicking which suggests there is not a seperate relay. There are 6 separate relays behind the UCH near the bulkhead but have removed each one by one and pressed the switch and you can still hear the click. Is there a separate relay for the rear demist and mirrors somewhere else or is it built into the UCH?


Thanks for your input.

F