Volkswagen Eos Forum banner

1 - 12 of 12 Posts

·
Registered
Joined
·
56 Posts
Discussion Starter #1
I'll start with assuring you all that I have read so many posts on here related to this problem before posting this that I'm fairly certain I've covered all the known everyday issues... I think.

My passenger window (LHS - UK car) will not operate from the passenger door switch. I cannot confidently say when it last worked but I've never known (owned the car for 7.5 years) a problem with it before.

I am in the process of selling my beloved Eos and went to to give it a good functional before someone came to see it. While operating the roof with everything working fine a few times then passenger window failed. The glass was loose and could be lifted freely, clearly a broken cable. It was and the full lifting frame has now been replaced using Vox's guide, thank you. I 'taught' the module (with the driver's switch) and the auto function operates. When I went to test the passenger switch I got nothing.

Again, using Vox's guide and his word document I tested the old switch and got 0.2 Ohms across term's 1 + 4 at all times regardless of operation. The switch connector only has 3 cables in and I'm presuming term 2 is the LED with 1 as the common and 4 as the signal to the module. I have no wiring diagrams though.

I ordered a new switch, when I test it I get:
Up ohmsDown ohmsUp 1 touch ohmsDown 1 touch ohms
Front left P1-P41801605250.3
Open circuit in the neutral position. The up resistances are clearly a little weird there.

Connected it (still with the outer door card removed) but there is still no window operation from that switch. All other functions (Driver's switch, 'all windows' switch, roof operation, lock/unlock frameless drop) operate the window.

The battery has died recently and was showing low V even after running the car for a while and having the charger on it. I have now fitted a new battery (Yuasa Silver 5000, 80Ah 760A) but the problem remains.

I have had my VCDS connected and scanned it so many times it's ridiculous but never had any error that might relate to that switch. All DTC's cleared and no faults showing anywhere now. I've also gone through the coding to see if there was a related setting and couldn't find anything.
 

·
Registered
Joined
·
5,475 Posts
Diagnostics won't report a switch problem. It can't report a switch that isn't operated!
Have you looked here?
I don't understand those resistances either. I guess you measured them, but my table also took into account the actual resistor values they used on their circuit board.
If the switch resistances are correct and the function still doesn't work, go straight to the fragile multi pin connector and check the wiring to it and look for any bad (bent or corroded) pins. It is easily damaged when people hang their door cards off it!

Because they are using resistances (i.e voltages) to select the functions, you only need to check the common and signal wires. There is some tolerance on resistance but not much, which is why some similar looking V.W switches with different resistor values do not work. However, if the zero ohm one touch doesn't work (after enabling/reset the function) or doesn't work on one side, there must be a wiring break between the signal and common and the main loom to the convenience unit.
 

·
Registered
Joined
·
56 Posts
Discussion Starter #3
Yes, that's one of the threads I was looking at and used your resistances table as a guide.

I wonder if, with only one signal line (P4) instead of two (P3 + P4) then the resistances have to be four different ones to give four different outcomes at the module.

I can only think that it's a loom issue now although I did try to be careful when removing and refitting the door cards and when testing.
Without the wiring diagram or an idea of what cables to test, where they are and what readings to expect then I don't know where to go next with this. I have examined as far as possible and there is no obvious damage to the cables or connector.
 

·
Registered
Joined
·
5,475 Posts
The switches all work the same way. Excluding the led, they only need 2 wires, a common ground (probably shared by the led?) and a single signal wire to the ECU for all functions. Zero resistance (short circuit) is reserved for 'one touch'. When you press a switch it selects either one resistance or a combination unique to that function. The wire to the ECU then converts this resistance to a voltage (0-5 volts I think) and that voltage determines what the switch does. Repeat for the other switches and the voltages will be different. Where there are multiple switches, they probably still use only one signal wire to the ECU.

If you check the voltage with a multimeter between the switch common wire and the resistance signalling wire with no switch pressed you should measure either 5V or 12V. Compare with the other side. If you measure no voltage at all then the wire either common or signalling to the ECU has broken. You can't check wires just by looking you have to use your ohmeter. If you get a voltage (which isn't the led wire) and operate the switch, this voltage will change and be different for each position of the switch. Obviously the one touch voltage will be maximum (switch open) or zero if closed.
 

·
Registered
Joined
·
56 Posts
Discussion Starter #5 (Edited)
Ok, this has forced me to dredge up some electrical and electronics knowledge. Lets see if you agree with my idea.

These are my results after some Voltage checks at the back of the connector with the switch connected and with respect to earth (body of the car). With the headlamps off.

Switch positionP1 BrownP2 Grey/WhiteP4 Purple/White
Neutral0V0V3.6V
Up3.6V0V3.6V
Up 13.6V0V3.6V
Down3.6V0V3.6V
Down 13.6v0V3.6V

This leads me to believe that P2 is the LED supply. P4 is the supply Voltage and P1 is the signal to the module.

As all Voltage must be dropped across a circuit, and I suspect there will be a control resistance in the module, there should be a varying amount of Voltage (based on my resistances in the original post) leaving the switch and then sensed at the module for each operation.

There appears to be no Voltage drop at all across the switch which leads me to suspect the signal cable P1 must be broken somewhere between the switch and the module.

Where is the module? Which module is it? 'Door Elect, Pass' ? Maybe I can continuity check the cable to confirm it. Then replace if possible. I've done full length aircraft rewires so I might be ok...
 

·
Registered
Joined
·
5,475 Posts
It can be misleading to use the car ground because it creates two fault variables - A broken ground wire to the switch or a broken signal wire. Since you are seeing a voltage (I said 5V but it could be 3.6V) in all switch positions with respect to chassis ground, it looks like you have lost the common ground wire connection to the switch. Nothing would work and the led won't light?

One pin (you say P4 but I think they say P1? has a brown wire on it. That should always measure zero volts wrt chassis. The fact it doesn't when you operate the switch means it's floating and seeing voltage from the resistors. This switch seems to have only 3 wires connected but there could be 4 terminals? If there are 4 terminals, one is a dummy with nothing connected to it. Is the connector plugged in the correct way?

You can confirm the common wire by connecting your ohmeter between the switch common wire (pin 1 brown?) and the chassis. If you don't get nearly zero ohms (short circuit), the wire is broken. If you get zero ohms on the wire then check it is connected to the correct pin on the switch.

If you connect a chassis ground wire link to the switch pin that has a brown wire on it (I think that's pin 1?) your switch should in theory work. If it does, you have to find the wire break which will probably be somewhere between the switch terminal and the bunch of wires comming into the car from that big cable grommet at the door front. You can use sewing pins pushed through the insulation to check continuity with an ohmeter. V.W often hide commoned wires like ground connections as a splice in their looms where there's a bulge.

You really need to think about a VIN matched workshop manual which has wiring and fuse diagrams specific to your car.
 

·
Registered
Joined
·
56 Posts
Discussion Starter #7
One pin (you say P4 but I think they say P1? has a brown wire on it. That should always measure zero volts wrt chassis. The fact it doesn't when you operate the switch means it's floating and seeing voltage from the resistors. This switch seems to have only 3 wires connected but there could be 4 terminals? If there are 4 terminals, one is a dummy with nothing connected to it. Is the connector plugged in the correct way?
I've edited my last post with cable colours now. P1 is the brown cable.
The connector will only go in one way. There are 4 terminals in the connector but only 3 cables connected to it. The new switch only has 3 pins anyway and match the 3 connected cables.


I've found the module. It's the one attached to the window motor. That was a face palm moment for me. sigh. There is one connector on it that has the three cables from the switch. I have continuity checked all 3 and they're all 0.2 ohms and Open Line to each other so it appears they're good.

I'll continue to investigate.
 

·
Registered
Joined
·
56 Posts
Discussion Starter #8
I did as you suggested and bypassed the brown cable P1 (from the back of the switch connector the the body) and the switch now operates the window. There was a small celebration there and a warm feeling of some kind of progress.

But I've checked that cable length (switch to module) with both ends disconnected and it's fine. Maybe another cable from the module to somewhere else (earth?) is broken, but how would that only affect the passenger switch? Head scratch

Could the module itself be knackered? How could I find out?
 

·
Registered
Joined
·
56 Posts
Discussion Starter #9
Right...!!! My window now works. It turns out the you can fit this connector into the module with the bit in the yellow circle but that doesn't make a good connection. If you use the bit in the green circle then it goes in a but further and all is good.

I hope this can help someone else avoid making such a silly mistake in the future. Now to finish rebuilding the door.

22599
 

·
Registered
Joined
·
5,475 Posts
Those are the locking connectors with fine pins I referred to. The pink locking lever has to be open for the connector to push right in over the pins, then the lever is pushed back to close the connector in further and lock it. For some of them they provide a couple of small holes to wire the lock bar closed to stop it unlocking. The drivers side has loads more pins connected and a much shorter wiring harness. I got fed up with the short looms on both door cards because sometimes I wanted my door cards connected for testing. With a bunch of single color wires, a sunny day, a chair and a pint, I cut every single wire and extended them with a solder sleeve and splice by about 12". :)I did the same thing for the rear tweeters, also on very short wires.

Still, you learned a lot about switches! Onwards and upwards.
 

·
Registered
Joined
·
56 Posts
Discussion Starter #11
It's silly how many different types of connectors there are on cars. Aircraft are way simpler. 😂

Thank you for all your help again.

Anyone want to buy an Eos ?? 😢
 

·
Registered
Joined
·
5,475 Posts
The few aircraft connectors I've met with MIL specs have decent gold plated pins and weather/moisture proof sealing glands and couplings, not like these cheap tin plated computer style connectors. Well, I think 25 pin serial 'D' connectors with ali headshells are far superior.
 
1 - 12 of 12 Posts
Top