Passenger Window Switch

[sotal]

I've started to have a look at why the passenger window switch doesn't work properly.

From the drivers side switch it goes up and down perfectly. However from the passenger switch it only goes down not up.

I have inspected the wiring in the hinges on both doors. The passenger side wiring looks perfect. The drivers side has split the insulation on two wires (orange wire and black wire) however the wire inside is still intact visually. I don't know if any of the wires are damaged inside.

The passenger window switch has already been replaced with no difference.

I attached the multimeter to the window motor on the passenger side. It has 2 wires that basically takes 12v on one wire and GND on the other - these are reversed to make the window go the other way. When I use the drivers switch this does as expected and shows something like 12v one way and -12v the other way. When I use the passenger switch it shows 12v when I press the switch but just stays at 0.00v when I pull the switch.

So at this point it just looked like a broken wire and still seemed fairly obvious.

However what has now confused me is that if I unplug the window motor and just connect to the wiring that would have supplied it, then when I press the passenger switch I get 12.1v when I press it down and 11.9v when I pull it up. However as soon as I connect the window motor again it just shows 0v when I pull the switch.

The only explanation that I can think of for that is a really bad connection (or nearly broken wire) that allows 12v with no current but as soon as it puts a load on it just shows 0v????

Does that sound right - any ideas on which wires to suspect? Or where to go next?

I'm currently looking at this...

http://www.g8dhe.net/bwm/bwmanualp.htm?1999/Page_106


Thanks

[g8dhe]

Yup, that's right it will have a high resistance, so as soon as you try to draw current the voltage drops away! Just follow the Black/Red wire back along to find the source of the high resistance connection, its the common connection of the passenger side switch to +12volts.

You better using the prepared link in the lower righthand corner "Embed code" of a BWM page as its set up to show an image and link the image to the actual page;

[sotal]

Having studied the above wiring diagram, I'm happy with how most of it operates but I do have a few questions.


I can see that the drivers side passenger window switch is the bit top right and the passenger side passenger window switch is the bit on the lower right of the diagram. I can see how it all works to switch the positive supply to the window.

What I can't see is how the motor gets a GND connection? Or is it just through the motor body and it just gets 12v on either of the cables supplying it?

Also on the wiring diagram there are little arrows on the wires with dashed lines going across - what do these mean?

And finally! What is X-17 and X-18?

Thanks

[sotal]

Yup, that's right it will have a high resistance, so as soon as you try to draw current the voltage drops away! Just follow the Black/Red wire back along to find the source of the high resistance connection, its the common connection of the passenger side switch to +12volts.

Thanks - wouldn't it use the black and red wire for putting the window down as well as up? I can see that it may be a little more load to lift a window than drop it but I would expect problems with it going down too?

What do you reckon?

[sotal]

I did some more testing.

At the motor there is a green wire and a red wire.

If I apply just 12v to one of these wires nothing happens. I have to apply 12v to one of them and GND to the other.

When I push the switch down I get 12v on the green wire and a good GND connection on the Red wire.

When I pull the switch it applies 12v to the Red wire but the Green wire is not a good GND connection. If I connect the Green wire to GND with an extra wire - then pull the switch the window goes up perfectly well.

So the 12v side of things actually seems to be fine, it seems to be the GND side. Obviously I can't leave the extra GND wire connected where it is as then I would connect 12v straight to GND when I press the switch.

What I can't figure out from the wiring diagram is how the GND side of things is switched?!

[g8dhe]

The ground comes from the Drivers side switch both sides are earthed via that route, and the local passenger switch removes the connection on one side or the other and connects the local +12volt power to it.

[sotal]

The ground comes from the Drivers side switch both sides are earthed via that route, and the local passenger switch removes the connection on one side or the other and connects the local +12volt power to it.

Ah that makes sense, I missed the GND connection coming through the disable switch on the diagram.

My only problem with that is again it doesn't make sense! It would use that same GND connection when the drivers door switch was used.

Any ideas?

[g8dhe]

Which is why I haven't been adding to the discussion much! I think you need to run around with the meter and check each point again, because something isn't quite making sense! If it works OK from the drivers side that should indicate that the ground connection is fine all the way thru but it would seem that isn't the case - or that there is still an intermittent in the loom itself .....

[sotal]

After looking at the diagrams again the only thing I can think is that the GND is a bit dodgy all the time but the UP from the passenger side is at the furthest point of the circuit with the highest load so it struggles.

If it is then the suspect wire would be the black one in the hinge on the drivers door where the insulation was damaged a little.

I will go and cut a section out and join in a new section and see if that works.

I have noticed that when winding the window down sometimes you have to press the button twice - the first time it does nothing. So maybe it is related.

[sotal]

I didn't cut and replace the damaged piece but I just tried bypassing it by attaching a wire from ground to the black wire inside the drivers door. This made no difference

I have just tested the switch again on the drivers side - just to make a slight correction. When monitoring the motor, when I pull up the switch the Red wire shows 12v - there is no continuity to ground on the green wire (as I said previously) However when pressing the switch (and the window goes down) there is 12v on the Green wire - there is still no continuity to ground on the Red wire.


If I connect the Green wire to GND and pull the switch up then the window goes up fine. Surely that must mean that the 12v supply side is all OK?

[sotal]

Have patched wires across from drivers door to eliminate any damaged wires.

Black/Red - made no difference
Orange - made no difference
Red/White - made no difference

I have also connected the black direct to earth from drivers door - still made no difference


I have done as suggested and retested the wires, I have made up a more secure system to make sure the probe doesn't slip off.

I have used the multimeter set to 20v. I have connected the black probe to the front 12v power socket earth. I am using the red probe to test the wires.

I tested the 2 wires going to the window motor under all the different scenarios I could think of.

Testing the Red Wire:

Using the Passenger Switch:

Pull - 12.1v at the Top
Pull - 12.1v whilst Moving up

Push - 0.3v whilst moving down
Push - 1.96v at the Bottom

Using the Drivers Switch:

Pull - 9.36v at the Top
Pull - 10.8v whilst Moving up

Push - 0.3v whilst moving down
Push - 1.8v at the Bottom


Testing the Green Wire:

Using the Passenger Switch:

Pull - 12.1v at the Top (can't hear it trying)
Pull - 12.1v whilst Moving up

Push - 12v whilst moving down
Push - 10.6v at the Bottom

Using the Drivers Switch:

Pull - 1.8v at the Top
Pull - 0.8v whilst Moving up

Push - 12v whilst moving down
Push - 9.4v at the Bottom



With nothing pressed at all they both read 0.00v and both have continuity to GND.


So the problem appears to be that when pulling the passenger door switch there is always 12v on both the green and the red wires.

The only thing left that I can think of is that somehow the drivers switch unit is faulty?

[g8dhe]

The drivers door switches are known for failing, so it might be worthwhile taking a careful look at it and seeing if there is any damage to the contacts. Watch out when taking it apart, the little spring that causes the toggling is likely to jump out and get lost!

[mikeonb4c]

The drivers door switches are known for failing, so it might be worthwhile taking a careful look at it and seeing if there is any damage to the contacts. Watch out when taking it apart, the little spring that causes the toggling is likely to jump out and get lost!

I dismantled mine with my hands and it inside a bucket so stuff couldn't drop to ground - worked a treat!

[sotal]

The drivers door switches are known for failing, so it might be worthwhile taking a careful look at it and seeing if there is any damage to the contacts. Watch out when taking it apart, the little spring that causes the toggling is likely to jump out and get lost!

Would it cause this fault though?!

Just tested the Orange wire and the Red/White wire at the passenger switch and both have good continuity to GND when nothing is pressed - so that appears that the drivers switch is doing everything it should at that point.

Starting to get frustrating now!

[g8dhe]

Rather than trying to measure the voltages I would pull the fuse and start measuring the resistance along each path from earth to passenger motor and from fuse to passenger motor, then whilst watching or listening to the buzzer if it has one, operate the switches and move the doors around and see what path gives a problem then start moving down the circuit till you can isolate the switch/loom/connector that is causing the problem.

Also bear in mind that there might just be more than one fault as well!