Hi All,

Had a search and can not find a diffinative answer, owners manual is not clear either.

On a 2012 AB, does the front and rear screen turn off automaticly? Do the heated mirrors turn on below a tempreture and with windows on only or automaticly?
Put my front and rear on this morning, drove to work, about 20 mins drive and they where both still on?

The front and rear heated windows can be programmed to come on automatically if the outside temp is below 2 deg c. The rear heated window switch also controls the heated mirrors which is on a timer. Usually about 10 minutes. I found that my heated mirrors were crap compared to other vehicles i drive with them. To the point i ask my dealer to check to see if they actually worked. The front screen is on a separate switch, and is also on a timer. So i would have thought 10-15 minutes tops, before they should switch off. Then again, we are talking about a L/R product that has more electrical gremlins than the rest of the entire motor industry put together.

lol might be a trip to dealers and there was no heat on the mirrors at all this morning and both front and rear where on for at least 20 mins and never switched off.

Hi guys,

The heaters are not as straight forward as we all think.
Here is a VERY detailed description and yes, mine are working correctly!
And who knew, heated mirrors are on more with your wipers!

Rear Window Heater
The ATC module controls operation of the rear window heater using medium speed CAN messages to operate the rear window heater relay in the central junction box (CJB). The control module in the CJB interprets the CAN messages and switches the ground connection of the relay coil to operate the rear window heater. While the rear window heater relay is energized, a battery power feed is connected to the rear window heater elements. Rear window heater operation is only enabled when the engine is running.
The ATC module operates the rear window heater in heating cycles of varying power and time. The heating cycle used depends on the ambient air temperature and whether it is the initial or subsequent operation during the current Power mode cycle.
When the rear window heater switch is pressed, the ATC module illuminates an LED in the switch and initiates the appropriate heating cycle. The LED remains illuminated until the rear window heater is selected off, the heating cycle is completed or the engine stops. If the engine stalls or turned off, rear window heating resumes if the engine is re-started within 20 seconds.
On the initial selection of rear window heating, the ATC module uses a short or long defrost phase at full power, followed by a low power phase. The defrost phase used depends on the ambient temperature. During the low power phase, the rear window heater relay is cycled off for 80 seconds and on for 40 seconds.
On subsequent operations, during the same Power mode cycle, the ATC module operates the rear window heater at full power for a fixed time period.

Rear Window Heating Phases

Phase Time, minutes
Short defrost (-5°C (23°F) and above)

10

15

20

10

3

5

10

3

Less 8 8 to 15 15 to 25 Over 25

Wipers Off 50% 33% 0% 0%

Wipers On 50% 33% 25% 0%

^^useful post^^

is it a given that heated mirrors are included on all RRSs?

I have to say, i've no evidence that i have them, seems to take an age to clear them of frost or dew, but maybe i should turn the wipers on more!

Having moved from a 2007 to a 2012 I too thought my heated wing mirrors weren't working so mentioned it the dealer when it was in they came back with the response above. It would appear that the elements cycle on and off but seem mainly to be off! If i'm lucky they might clear after my 15 minute commute to work...such a shame the 2007 mirrors cleared so quickly..

My L494 sits out on the drive all year round and I have never noticed the heated wing mirrors come on, during the icy spell we had in November I had my front windscreen replaced and now there is a sizable delay between it coming on and the rear one coming on, the rear can be almost defrosted before there are any signs of life from the front screen, I wonder if it is part of the Battery managament system to reduce cold weather load on the battery? 2020 Pangea Green 1st Edition D240 New Defender 110 is here and loving it
2018 Melting Silver Mini Countryman PHEV - soon to be replaced
2015MY Corris Grey SDv6 HSE Dynamic, the best car I have ever owned, totally reliable only a cou0le of rattles in 3 years, now no longer in my care
Also in my garage is a 1996 TDi300 Defender 90 County HT made into a fake CSW

On the early RRS the mirrors were on too much if anything
One day they might get the right balance.

It sounds like your replacement windscreen isn't very good! or maybe not a genuine part. That is a real shame.

I'm fairly sure the battery management has a priority system. And priority No,1 would be the drivers side of the front windscreen.

1JBS wrote:

Having moved from a 2007 to a 2012 I too thought my heated wing mirrors weren't working so mentioned it the dealer when it was in they came back with the response above. It would appear that the elements cycle on and off but seem mainly to be off! If i'm lucky they might clear after my 15 minute commute to work...such a shame the 2007 mirrors cleared so quickly..

Parking on London streets, I fold my mirrors in and they don't seem to require defrosting in the morning because of this

yeah it's a good plan on cold nights.

make it easier to shift most of the ice of the windscreen too.