Disco 2 Electric windows & BCU

My 2002 Disco 2 has developed a fault with the LH Front window not opening. I have trawled through all the relevent threads on here and elsewhere but the key different symptom I'm getting to all threads I've read is that when I press the switch down I do not get a clicking noise at the BCU, whereas when I press it up I do.
So far, I have:
1. Swapped the RH and LH switches. LH switch operates RH window perfectly but RH switch doesn't operate LH window. (only click on window up)
2. Checked I have a good earth on pin 1 of the switch connector.
3. Checked the wiring between door and door pillar
4. Checked for loose connectors,etc.

Because I'm not getting a click from the BCU when I press the switch down, I haven't bothered to take the door apart to check the motor. To my mind, I think the fault is either in the BCU or wiring to the centre console switch, but please tell me if you disagree.

Has anyone seen this before?

speggo said:

Because I'm not getting a click from the BCU when I press the switch down, I haven't bothered to take the door apart to check the motor. To my mind, I think the fault is either in the BCU or wiring to the centre console switch, but please tell me if you disagree.

Click to expand...

I don't disagree, check the continuity between that switch and BCU eventually give earth with a wire directly to C0662 - 1

I tried to put an earth into CO662-1 but not sure I managed to make a connection. Maybe I'll try the old pin through the wire trick.

I have very recently had a similar if not the same problem.
If you have swapped the switches and both work the right hand window but neither works the left hand window then I have various suggestions.

My left hand front window stuck in the down position. When operating the switch all I got was a bit of a click from the motor/ drive in the door.I unbolted the motor and mechanism, pushed the window up into place and jammed it there with bits of wood.
Months later I took the mechanism from a spare left hand door and replaced the one in the car with this, it now works.
So I stripped down the original faulty mechanism.
I discovered that the motor had a lot of water in it, in fact there is a funny right-angled tube on it presumably to drain water from it.
I also discovered the mechanism was extremely stiff, the central hinge point was in dire need of lubrication and it was obvious that a former owner had tried to lubricate the mechanism, but had not done it properly. The cogwheel had gone to the end of the quadrant and jammed there as the 3 bolts holding the mechanism to the motor were slightly loose. The clicking was caused by the cogwheel trying to engage with the quadrant.
I connected a 12 volt battery to the motor, on its own, it turned, better in one direction than the other, but it ran. So I cleaned it out as best I could without removing the armature fully, and lubricated it. I also freed off the quadrant and lubricated it.
Once all connected back up again and the motor mounted on the quadrant, the whole mechanism worked fine. I am thus keeping it as a spare.
To eliminate the BCU completely, I suggest you disconnect the plug at the door hinge.

If you can find the requisite pins, you could use them to see if 12v negative and 12v positive, applied to both sides of the motor, in turn will make it work in both directions. Grey with red trace and grey with blue trace, leaving the BCU, makes the motor turn in either direction to raise the window. According to the wiring diagram from the RAVE manual for MY2000. These wires change to grey/pink and grey/blue just before the motor itself. You will only find this out by getting the door card off etc!
But I tested mine by simply connecting from the batt to the pins on the motor. If when you swapped them, the LHF switch works the RHF window then the earth should be OK as it is the same for both. Page 13.31 of the Haynes manual slightly simplifies this and differs in one way, it states the two wires from the BCU to the motor are Grey/black and Grey/Red, (I think the black trace may be a mistake but I am not about to take my door apart or go hunting in my box trailer in the dark to find out!) and it does not mention the wire colour changes inside the door!
I bow, as always, to Sierrafery's knowledge of the electrical system on the Disco 2, and I can only go by RAVE and this is for LHD vehicles, but I imagine this may well be the same for RHD vehicles.

So, to sum up, I think you will eventually find the problem is more to do with the motor and the mechanism, but I cannot be certain.

If you do decide to take the door card off, having done all this and taken some photographs, I remain ready to help should you need it. Fortunately, getting the mechanism out when it is at the bottom of the door is much easier than when it is at the top. Just one thing, when removing the inner waist seal, i.e. the rubber/metal strip that presses against the glass from the inside, do take it very carefully, cos they can bend very easily, the official way of doing it is to free off the clips working from the two ends towards the middle. I am still waiting for the replacement for mine from Craddocks and they ain't cheap either. I do have a reasonably straight one from one of the two doors but I'd rather use a new one as it is so obvious.
But I'll let you get on.
Best of luck.

Any further on with this?

Stanleysteamer said:

Any further on with this?

Click to expand...

Thanks for asking! I have made a little progress in that I have discovered that earthing pin CO662-1 as suggested by Sierrafery now produces a click at the BCU. This suggests that I have a broken wire/earth issue between the switch and BCU. Unfortunately, although the BCU clicks, the window still does not open.
I have just removed the door card but haven't quite worked out which wires go where, or the best way of putting 12v across the motor to see if it is OK.
Any help/suggestions gratefully received!

Grey/pink(SK) and grey/blue(SU) wires to pins 1 - 2 of C0326 are for the motor, for down operation SU - earth, SK - live... make sure that the motor is not stuck cos then the BCU cuts the feed so measure voltage across those wires at the motor with connector unplugged when you get the click from the BCU to see if it gets there or not

So now I really am confused! I put 12v across the motor and can drive the window up and down. So I drove the window half down and reconnected CO326 and discovered that both operating the up switch and earthing CO662-1 caused the window to drive UP. Also measuring across CO326 open circuit, I can only get +12v on Grey/Blue(SU) and not on Grey/Pink(SK), so no reversal of voltage.

speggo said:

Thanks for asking! I have made a little progress in that I have discovered that earthing pin CO662-1 as suggested by Sierrafery now produces a click at the BCU. This suggests that I have a broken wire/earth issue between the switch and BCU. Unfortunately, although the BCU clicks, the window still does not open.
I have just removed the door card but haven't quite worked out which wires go where, or the best way of putting 12v across the motor to see if it is OK.
Any help/suggestions gratefully received!

Click to expand...

Right I'll put some pics up but if you have got the door card off it makes sense to get the whole thing out and test it.
Get the plastic sheet cut back, you only need to cut into the bottom part. Thread the speaker wire through the plastic sheet, under the gaffer tape, then fold it back, securing it up out of the way with a bit(s) of tape.

Here you can see the six bolts that hold the mechanism to the door frame, you will also see the circular hole cut in the metal that will allow you to disconnect the wire from the motor. Also to be seen in the trangular hole to the right of this. The bottom of the quadrant is visible as is the side-entry bar. The obvious part of the loom goes off to the door mechanism.
Here is a close up of the plug.


And here is how it comes off. you have to prise up a bit of plastic at the top and prise the plug away, left to right.

Here is the mechanism still attached to the window glass but all slid down to the bottom of the door. You can just see the two bolts, one at each end of the bottom of the glass connecting the runner to the mechanism.

The mechanism is attached to the bottom of the window glass with two bolts, the left hand one is much easier to get at than the other one. The right hand one can be a right bitch to get at and get undone. I had to do one of them unseen with a spanner as opposed to a socket. This image was taken after I took it off, tested it and put it back on again to ensure I could do it on the car! Much easier if the glass is in the down position before the motor fu cks up!
Close up of these two bolts. left first.


And the real sod, the right one.


Once you have got those both off then you can wiggle the mechanism free with the motor attached. Then once you have got the motor off (Three torx headed bolts) the two terminals are obvious and you can test the motor with wires direct from a battery, or simpler, just put the plug back in and test it on the car.
You may, as I have explained already, find the motor with lots of water in it. Just pull fairly gently on the armature at the gear end and it will come forwards just a bit and you can shake the water out, then spray WD40 down into it to get the rest out, then spray lubricant into it to keep it from doing any harm. I did ask on my own thread on this about what lubricant to use and in the end used a WD product that I knew still conducted electricity cos I tested it with my meter!
The mechanism you may well find is very stiff at the big central pivot point. A bit of penetrating oil followed up by movement to and fro then grease should sort it.
All this is presupposing there is not actual damage to the quadrant or the gears, but the big gear is not plastic which is in its favour.
Putting it all back together is not so bad as you can use the motor to position the quadrant/mechanism to make it easier to get the six bolts back in.
I found the biggest PITA was getting the plastic pins in the door card to line up and go back together properly. It took me about 4 or 5 goes and I had a full set of spare pegs. I needed them all!
Best of luck and do get back to us and tell us how you got on!

Stanleysteamer said:

Right I'll put some pics up but if you have got the door card off it makes sense to get the whole thing out and test it.
Get the plastic sheet cut back, you only need to cut into the bottom part. Thread the speaker wire through the plastic sheet, under the gaffer tape, then fold it back, securing it up out of the way with a bit(s) of tape.
View attachment 212393
Here you can see the six bolts that hold the mechanism to the door frame, you will also see the circular hole cut in the metal that will allow you to disconnect the wire from the motor. Also to be seen in the trangular hole to the right of this. The bottom of the quadrant is visible as is the side-entry bar. The obvious part of the loom goes off to the door mechanism.
Here is a close up of the plug.
View attachment 212395

And here is how it comes off. you have to prise up a bit of plastic at the top and prise the plug away, left to right.
View attachment 212396
Here is the mechanism still attached to the window glass but all slid down to the bottom of the door. You can just see the two bolts, one at each end of the bottom of the glass connecting the runner to the mechanism.
View attachment 212397
The mechanism is attached to the bottom of the window glass with two bolts, the left hand one is much easier to get at than the other one. The right hand one can be a right bitch to get at and get undone. I had to do one of them unseen with a spanner as opposed to a socket. This image was taken after I took it off, tested it and put it back on again to ensure I could do it on the car! Much easier if the glass is in the down position before the motor fu cks up!
Close up of these two bolts. left first.
View attachment 212399

And the real sod, the right one.
View attachment 212400

Once you have got those both off then you can wiggle the mechanism free with the motor attached. Then once you have got the motor off (Three torx headed bolts) the two terminals are obvious and you can test the motor with wires direct from a battery, or simpler, just put the plug back in and test it on the car.
You may, as I have explained already, find the motor with lots of water in it. Just pull fairly gently on the armature at the gear end and it will come forwards just a bit and you can shake the water out, then spray WD40 down into it to get the rest out, then spray lubricant into it to keep it from doing any harm. I did ask on my own thread on this about what lubricant to use and in the end used a WD product that I knew still conducted electricity cos I tested it with my meter!
The mechanism you may well find is very stiff at the big central pivot point. A bit of penetrating oil followed up by movement to and fro then grease should sort it.
All this is presupposing there is not actual damage to the quadrant or the gears, but the big gear is not plastic which is in its favour.
Putting it all back together is not so bad as you can use the motor to position the quadrant/mechanism to make it easier to get the six bolts back in.
I found the biggest PITA was getting the plastic pins in the door card to line up and go back together properly. It took me about 4 or 5 goes and I had a full set of spare pegs. I needed them all!
Best of luck and do get back to us and tell us how you got on!

Click to expand...

In the time it took me to get the pics of the camera, modify the images, save them all, then upload the pics toghether with the text, I discover you have found that the motor and mechanisma are OK!
What a prat I am!

sierrafery said:

Grey/pink(SK) and grey/blue(SU) wires to pins 1 - 2 of C0326 are for the motor, for down operation SU - earth, SK - live... make sure that the motor is not stuck cos then the BCU cuts the feed so measure voltage across those wires at the motor with connector unplugged when you get the click from the BCU to see if it gets there or not

Click to expand...

Stanleysteamer said:

Grey with red trace and grey with blue trace, leaving the BCU, makes the motor turn in either direction to raise the window. According to the wiring diagram from the RAVE manual for MY2000. These wires change to grey/pink and grey/blue just before the motor itself.

Click to expand...

As I said in post #4!!!!!!!!!!

Steam coming out of ears now!
Why do I bother!!!

speggo said:

So now I really am confused! I put 12v across the motor and can drive the window up and down. So I drove the window half down and reconnected CO326 and discovered that both operating the up switch and earthing CO662-1 caused the window to drive UP. Also measuring across CO326 open circuit, I can only get +12v on Grey/Blue(SU) and not on Grey/Pink(SK), so no reversal of voltage.

Click to expand...

Ok, I've calmed down now.
You know that the switch works as it drives the other window when you connected it up, so it can't be that. It now looks like a problem at the BCU so I will simply say, if it was me I'd find a way of wiring the motor that cuts out the BCU. (The purists here will now be shocked, or maybe not, if they know me!)
I'd wire it so it takes power from the "igntion on" feed to the switch, and then off to the motor. Then at least the bloody thing would work. While you p!ss around with the BCU. Ok it won't go down by itself and stop at the bottom, but then electric windows never used to, so old skool rules!
I give up!

Hey Stanley... this issue has nothing to do with the mechanism

speggo said:

So now I really am confused! I put 12v across the motor and can drive the window up and down. So I drove the window half down and reconnected CO326 and discovered that both operating the up switch and earthing CO662-1 caused the window to drive UP. Also measuring across CO326 open circuit, I can only get +12v on Grey/Blue(SU) and not on Grey/Pink(SK), so no reversal of voltage.

Click to expand...

I don't really understand what you are doing there, if you know how to work based on the diagram it should be quite simple but the diagram can be wrong too as to mix up wire colours so you'll have to figure it out yourself, i cropped the relevant part:

sierrafery said:

Hey Stanley... this issue has nothing to do with the mechanism
I don't really understand what you are doing there, if you know how to work based on the diagram it should be quite simple but the diagram can be wrong too as to mix up wire colours so you'll have to figure it out yourself, i cropped the relevant part:

View attachment 212416

Click to expand...

At the point where he asked for more help I thort it was possibly mechanical hence my stupid post, but yes, you are right. I hand over to you as you is the man when it comes to all this stuff. I'm going to the bottom of the garden to eat worms!

Hey Guys, I'm very grateful to you both for taking the time to help me. I'm wondering if there is an issue with the wiring between the switch and the BCU. I think my next move will be to try earthing what should be the UP feed at CO660-18 to see what happens. I'll let you know how it goes.
Following on from Stanley's suggestion, did I see that it is possible to buy an aftermarket kit to bypass the BCU?

Thanks again guys

speggo said:

Hey Guys, I'm very grateful to you both for taking the time to help me. I'm wondering if there is an issue with the wiring between the switch and the BCU. I think my next move will be to try earthing what should be the UP feed at CO660-18 to see what happens. I'll let you know how it goes.
Following on from Stanley's suggestion, did I see that it is possible to buy an aftermarket kit to bypass the BCU?

Thanks again guys

Click to expand...

Mate, if you take my advice on electricamagoogly you really do take a risk.
My competence ends when fuel injection started!
I did not say that a kit was available to do anything! I did say I'd make one up for myself!
From my reading of the wiring diagram, the change of polarity is carried out at the BCU cos the diagram does not show a double pole/double throw switch. see this to unnerstand how one works. https://www.instructables.com/id/HO... need to control,going to the linear actuator.
With only three wires to the switch and two to the motor even to me this is pretty obvious. But you could fit an aftermarket DP/DT switch, or even, with a bit of cleverness and extra wires and maybe relays, make up a system that still uses the original switch. But this is sticking an Elastoplast over the problem rather than fixing it.
I think we have to ensure all wires to and from the switch and BCU, and BCU and motor are sound. If not you can fix them, just use a meter to check each wire from one end to the other and expect the broken wire to be where there is flex and friction. If they are sound then it may (must?) be a problem at the BCU. hopefully @sierrafery will be able to help you there. (I am now going to put my tin hat on and sit in a trench!)

speggo said:

I think my next move will be to try earthing what should be the UP feed at CO660-18 to see what happens.

Click to expand...

Doing that should happen exactly what happens when you push the switch for UP which you said it's working

sierrafery said:

Doing that should happen exactly what happens when you push the switch for UP which you said it's working

Click to expand...

So I have for the sake of my sanity rechecked what I checked previously. The current situation is:
1. Operating the switch only produces a click at the BCU when the UP switch is operated.
2. Earthing pin CO662-1 produces a click
3. Measuring the voltage at the motor connection produces SU live SK earth (window UP) for points 1 and 2 above, i.e. no reversal of voltage from BCU.
4. Shorting pins 1 and 3 at the switch produces a click. Shorting pins 1 and 4 produces a click.
5. I have also physically swapped the RH and LH front switches. RH window operated correctly.

My conclusions so far:
1. I have a poor/no connection between LH switch connection and switch. ( Point 4 & 5 as evidence)
2. There is a fault in the BCU which is causing the voltage reversal to fail. (point 3 as evidence)

In summary, I have learned a lot about the window circuitry, but am no further forward in finding a fix without replacing the BCU. As always, please let me know if you can think of anything else to check, or disagree with my conclusions so far.

Thanks

I'm confused now by point 3 so do you say that earthing C0662 - 1 gives voltage for window UP ?...it means that the diagram is wrong though i dont understand what you mean by "reversal voltage from BCU" the BCU switches polarity across the two wires to the motor so earth - live to one direction and live - earth for the other

one last scenario can be that the SK wire to have a short to earth so when the BCU sends earth to it and live to the other the motor works UP cos it gets what it needs but when it sends live to the SK wire the voltage drops due to the short and the BCU cuts the feed like when the window is already down ... to 100% confirm if it's the BCU at fault or not you'll have to unpin terminals from C0664 pins 1 and 4, connect the voltmeter in the cavities and switch to down, if you get voltage it's a short to earth in the wiring(it used to be chafed where the loom enters the door)...if no voltage the BCU is fubar