tomanytoysuk
New Member
Hi all, just a quickie is the rear heated switch the same plug configuration as the front just a different picture on the front.
PaulMc
Active Member
Internally, both switches are wired the same -
Pin 1 - From BCU
Pin 2 - Dash illumination live
Pin 3 - Not used
Pin 4 - Earth
Pin 5 - Warning light live from BCU
They both work by making a momentary path to earth (from Pin 1 to Pin 4), which the BCU detects and switches-on the requested screen.
While the screen is 'on', the BCU also provides a live to Pin 5 to light the switch warning light.
If climate control is fitted, pressing the 'defrost' button also instructs the BCU to switch on the front and rear screens.
The heated rear window switch uses a Black switch connector.
The heated front screen switch uses a Green switch connector.
These connectors are not interchangeable, unless you pare-off the keyways on the connector.
If you want to change the connector shell for the correct one, I sell them on eBay (see link in signature).
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tomanytoysuk
New Member
Big thanks paul
tomanytoysuk
New Member
Hi just one more question ,can I take feed wire going to the rear switch ,splice into into it and put the feed into the front heated window switch or will this be to much for the BCM.
PaulMc
Active Member
The wires used by the BCU to detect the front or rear window switches being pressed, come from different terminals on the BCU's connectors.
What is it that you're trying to do?
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discodrivercumbria
Well-Known Member
have you got a front screen switch?
like wise! what is it you are trying to do?
i have just put heated screen into mine , got new switch from landrover,
tomanytoysuk
New Member
Hi . I have got a rear heated window switch in place of the front one, next week I'm having the front windscreen replaced with a heated one , what I'm trying to get round is going to land rover for them to activate the BCM , just trying to find a cheaper option.
PaulMc
Active Member
If you can find someone near you with a Nanocom or Hawkeye, I'm sure that they would enable the heated windscreen for a couple of :beer2:
www.discovery2.co.uk/ Nanocom Locator, get help from your Land Rover Buddies!!!
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discodrivercumbria
Well-Known Member
cmryan
Member
Hi I have a problem with my front windscreen demister not working. It''s a D2 2001 that has a heated front windscreen factory fitted. When I press the dash button nothing happens, no light, no relay click. I have just replaced the missing relay with the correct part. Both fuses f7 and f8 are fine. Here is what I have found:
I have 14v at the relay on 2 of the 4 pins.
I have 0v at the purple wire at the switch
I have 0v at the screen connector in the rain gutter
I haven't tested the timer unit because I don't know where to find it. Having power at 2 of the relay connections tells me that the relay is getting power and should activate, and logic says that the switch has operated the circuit. Any suggestions anyone?
Thanks, Chris
I have 14v at the relay on 2 of the 4 pins.
I have 0v at the purple wire at the switch
I have 0v at the screen connector in the rain gutter
I haven't tested the timer unit because I don't know where to find it. Having power at 2 of the relay connections tells me that the relay is getting power and should activate, and logic says that the switch has operated the circuit. Any suggestions anyone?
Thanks, Chris
PaulMc
Active Member
The dash switch is a non-latching momentary switch, which switches a wire from the BCU to earth.
This signals the BCU to switch the heated windscreen relay's coil to earth, which it does for the timed period.
During the timed period, the BCU supplies a live to pin 5 of the dash switch, in order to illuminate the switch's tell-tale LED.
Check that the dash switch's earth, on pin 4, is OK - if the switch's night-time illumination works with sidelights switched on - then, the earth is OK.
You will also need to check that the BCU has the heated windscreen option enabled - you'll need an appropriate tool to do this - Nanocom, Hawkeye, etc...
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This signals the BCU to switch the heated windscreen relay's coil to earth, which it does for the timed period.
During the timed period, the BCU supplies a live to pin 5 of the dash switch, in order to illuminate the switch's tell-tale LED.
Check that the dash switch's earth, on pin 4, is OK - if the switch's night-time illumination works with sidelights switched on - then, the earth is OK.
You will also need to check that the BCU has the heated windscreen option enabled - you'll need an appropriate tool to do this - Nanocom, Hawkeye, etc...
.
cmryan
Member
Thanks Paul, I'm pretty sure the night illumination works. I will try to get a diagnostic tool on it. I can't imagine why the screen would be switched off but it's worth checking. Do you know where the timer unit is situated in case this is faulty? I unscrewed the dash fuse box today in case it's behind it but couldn't see the grey unit I've seen pics of online. Incidentally the rear demister works OK. Is this on the same timer or does it use a separate unit?
Maxwell85
Member
Just a quick one, its kind of in the same ball park. Could you theoretically remove the rear windscreen cables and use them to power an led light. Electrics is not my strong point but am I right in assuming that one cable is + and one is - and so I could just plug it straight in?
Nodge68
Well-Known Member
You could. However the power will only be there when the engine is running, and has a timer of about 10 minutes or so. Why not just run more wires, with a separate switch?
discool
Well-Known Member
sierrafery
Well-Known Member
discool
Well-Known Member
The glass bit in the tailgate door.what's that ? ...rear windscreen
sierrafery
Well-Known Member
It means i missread this thread's title then
Ctrl_alt_del
Member
I'm about to put a heated windscreen in my Discovery 2, I've got the switch and Relay.
Where does the relay need to go?