Rear window heating element keeps coming automatically? - Page 2

Mike Noc · 26th June 2012, 08:19

The reason it was fitted is so everything works well for different conditions without you having to do anything. As the old advert used to say 'Relax it's a Rover'.

The alternators are more than up to the job of charging the battery and running the accessories.

Flat batteries in winter are more often than not a sign that they are failing and need replacing.

Mike

I see MrDoodles beat me to it.

ROVERX501 · 26th June 2012, 12:27

Quote:

Originally Posted by Forestgreen

Hi folks, I read somewhere that if the outside temperature was less than 10 degrees C, the rear window element automatically comes on as the car thinks you might need to remist the glass, like it's winter. And this was suggested as being a bit of a nuisance as it could deplete the battery so a good idea to check if this happens and turn the element off if it comes on automatically unless the window really needs demisting.

On several times in the past few weeks both in the mornings and evenings if I've been using the car I've noticed that the rear window heating element comes on when I start the car. And the temperature in the message centre typically gives a reading of less than 10.

Is there a problem with my car, or are we just having a particularly British summer this year?

Well there you go, I wondered if this was a fault with mine, obviously not

Devilish · 26th June 2012, 18:29

Quote:

Originally Posted by raykay

The temperature sensor is used by other components as well, so although it would stop the HRW switching on, it could affect some other functions.

Severing the signal to the switch will not affect the ATC, even if I have to make the BCU and ATC think it has turned on the HRW, as soon as I get a window with all the elements working or repair mine, one way or another it will be done, might do a how to if I remember to take some pics.

raykay · 27th June 2012, 08:06

The temperature signal does not go to the switch.

The HRW is either switched on manually by operating the switch, or automatically by the BCU - the ATC unit receives the temperature signal from the instrument pack via the K-Bus, and if low enough, passes the signal, again via the K-Bus, to the BCU to switch on the HRW.

berkshirelad · 27th June 2012, 11:00

And presumably via K-bus to the dash temperature display.

I also think that the sensor is used for those of us with FBH as well.

tomijon · 27th June 2012, 11:09

No, the FBH sensor is nothing to do with the ATC. The atc uses the ambient air sensor, but both are situated very close together behind front bumper.

26th June 2012, 08:19	#11
Mike Noc This is my second home Rover 75 CDT Manual Connoisseur SE, Rover 75 CDT Automatic Connoisseur SE & a Freelander Td4. Join Date: Jul 2009 Location: Hampshire Posts: 11,570 Thanks: 3,470 Thanked 3,119 Times in 2,247 Posts	The reason it was fitted is so everything works well for different conditions without you having to do anything. As the old advert used to say 'Relax it's a Rover'. The alternators are more than up to the job of charging the battery and running the accessories. Flat batteries in winter are more often than not a sign that they are failing and need replacing. Mike I see MrDoodles beat me to it. Last edited by Mike Noc; 26th June 2012 at 08:22..

27th June 2012, 08:06	#14
raykay I really should get out more....... Now Other Manufacturer Join Date: Nov 2006 Location: Co. Kerry Posts: 2,786 Thanks: 16 Thanked 310 Times in 283 Posts	The temperature signal does not go to the switch. The HRW is either switched on manually by operating the switch, or automatically by the BCU - the ATC unit receives the temperature signal from the instrument pack via the K-Bus, and if low enough, passes the signal, again via the K-Bus, to the BCU to switch on the HRW.

27th June 2012, 11:00	#15
berkshirelad Gets stuck in Rover 75 Tourer Connoisseur SE Join Date: Jan 2012 Location: Newbury Posts: 836 Thanks: 9 Thanked 101 Times in 91 Posts	And presumably via K-bus to the dash temperature display. I also think that the sensor is used for those of us with FBH as well.

27th June 2012, 11:09	#16
tomijon Loves to post R75 2.5 V6 Conteparary + MGTF 135 Join Date: Mar 2008 Location: Liverpool Posts: 328 Thanks: 42 Thanked 12 Times in 10 Posts	No, the FBH sensor is nothing to do with the ATC. The atc uses the ambient air sensor, but both are situated very close together behind front bumper.