Hi Everyone,
I had the car into the auto electrician last week, and I was told that the window controller was causing a drain on the battery. It turned out it was a VW part, and I have fitted it today and it's all gone Pete Tong.

• The driver's window is the only one that moves
• The central locking doesn't lock
• The alarm doesn't arm

I have looked at the old unit and the new one, and it seems there are more connections on the VW part, could this be the problem? Or is the problem elsewhere? Are the switches sticking?




All Help Welcomed!!
Simon

 

Look to see what connections are actually made on the plugs - should probably be only the same ones...

Unplug the module do the central locking & alarm work then? This module does not control either function - but it does connect to the lock/arm connection (just to monitor it).

Alan

 

Yep.
Any Ideas?
It's a '90 car by the way. Won't this be connected to the alarm by the function that shuts all the windows when you lock the car?

Simon.

 

Yes - thats the connection to the lock switch (but as an input only)...

If nothing else you have a set of spare parts... should do better than that though.

Does you current draw go away with just the porsche unit unplugged?

If it comes to opening it up please post a picture of the innards before you scavenge parts... did you try to resolder the Porsche unit as discussed previously?

Alan

 

No, this is a new part I've just bought. Yes the drain drops as soon as the unit comes out.

What could it be!?

 

Could it be a connection going to the box has come loose? It makes no sense!

 

Right, some progress. The VW unit won't work, there are a different number of relays within it, not enough for the 928. £40 up the shute!

I contacted Paul Anderson here in the UK, and he said try the window switches, just to be sure. He has never heard of these boxes failing! Could it be just one wire isn't making a good enough connection to the box and is causing a small drain? It's only 0.4amps!!
It sounds unlikely, but the fact one wire wasn't connected to the vent switch in my car caused weeks of problems with the alarm and central locking!!
I'll take the plugs apart this weekend and see what's what, and clean up the switches.

 

I'm reluctant to bring up my epic battle with this window controller and parasitic draw. Suffice it to say that it may draw power for 45 minutes after the ignition is switched off, like the fan controller, according to this.

 

It could just be that the unit isn't powering down when the ignition is off. It is supposed to shutdown when the ignition is off and a door is opened.

Do your interior lights work from both doors...? if not it may never know it should turn off...

If this is the case you will need to either fix at least the door pin switches or work around this by intercepting the wire from the pin swithches and making it turn off immediately when the ignition goes off.

Alan

 

Well, before the electrican saw it, the door contacts didn't work, but now I have sire brushed them and fixed them. Now all the lights work. I'll do what is says there, putting the multimeter there before you disconnect the battery to save having to wait 40 mins!
There may not even be a problem anymore!!

But that says anything over 0.03amps is a problem, and the draw is 4!
Could this first 40 mins account for 3.7amps?

 

Any ideas?

 

rawky:

You should go through the standard parasitic draw process of attaching a good ammeter across the battery ground at least 45 minutes after the car was last driven and the ignition was last on. Then pull the ground cable end off the body so the ammeter is now providing the ground. Set the ammeter down so you can read it through the closed hatch. Close all the doors and wait for the lights to go out. The reading should be 30ma. I usually won't fuss too much if it is 50 or less.

If it's more than that, expose the central electric panel, do something to hold the passenger door pin as if the door were closed so the interior lights go off and stay off, and start pulling fuses. If you suspect the window controller, you could pull fuse 18 first and see what that does.

Here is my epic battle with the window controller. I had some parasitic draw and other bizarre behavior in a 90 S4.
https://rennlist.com/forums/928-foru...l-problem.html

Anyway, report your results from pulling fuses. Hopefully that will locate the circuit and we can go from there.

BTW, I do have a spare good controller if you want to borrow it. They are expensive.

 

rawky:

Here's some more about the same car.
https://rennlist.com/forums/928-foru...rent-draw.html

Note post #5 in the above thread. I may have overlooked that the switches provide ground to the controller. In my diagnostic test, I disconnected the switches and still saw parasitic drain, so I thought that ruled out the switches. Brent's comment there may be pertinent. Alan is our resident electrical expert. He should amplify on this.

4 amp is huge. Way huge. I never saw more than 150ma attributable to the window controller not shutting off.

 

Thanks for the reply, I am going to dedicate my morning to finding this one out!!
I'll come back to you with my findings
Simon

 

Ok, there was a 0.22 amp draw (220 mA), when fuse 18 was pulled the car locked, and draw eventually dropped to 0.03 amps (30mA) PERFECT!. So we know that the problem is on this circuit, do I need to borrow a power window regulator to eliminate this from the equation? Or is there some other checkpoints I should look through first?

Thanks,
Simon