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Discussion Starter #1
Hi, I'm new here, but I hope someone on this forum has run into a similar problem and can maybe help.
I have a 2008 EOS; lovely car but the roof stopped working a while back and I've been trying to fix it ever since. A VW dealer will charge me more than the card is worth to fix it (I've already tried and ended up paying 150E for basically a diagnostic check).
What happens when I try to operate the rood, is the windows go down, the sunroof slides about half way an then stops: on the dashboard "system fault" shows up
I have a vcds and can see the error code. Two errors come up: roof pump temperature too high, and open circuit short to ground ( the dealer showed me a current flow diagram and V118 - roof actuation hydraulic pump was marked as faulty ).
The thing is, the pump is ok...if I connect 12V DC to it, it spins. and I have 3 of them, I already tried swapping it out.
The solenoids are ok..I measured them and swapped them around. So maybe it's the ECU? but how can I diagnose that?
Maye worth mentioning, I lost a good bit of hydraulic oil while swapping out the pump/solenoids so now it's just below the min mark. But I had the same error before, I would not think this has anything to do with it. And I already ordered some hydraulic fluid, I'll top it back up once I get it.
Anyone have any suggestions? tips? advice? I'd really appreciate it.

Cheers!
 

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You will find what you need to test the roof pump and more here. Don't forget to look at the results form attachment! ...and you haven't confirmed you tested the pump temperature sensor?


And yes the roof controller itself could be faulty, but unless you know fixing boards full of SMD components, I would leave that until later. But it won't hurt to remove each connector and check for water damage on the pins and sockets. You can also test to see if power gets to the pump socket at the start of the roof cycle when the pump connector is disconnected. If no power and you still get the short circuit message your problem could be pump wiring, connectors or a short circuit Mosfet 'H bridge' which you can Google.

Good luck
 

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Discussion Starter #3
I read the info on that thread and I'll give it a go.
A few things I did try:
  • I visually inspected all the connectors to the ECU; they looked fine, but I cleaned them anyway
  • I checked the cable leading to the pump and solenoids, for continuity and a possible short circuit (any of the cables making contact with each other) and everything was fine
  • I measured the pump connector and it is getting 12V
One thing I did not quite get from the link you sent me is the part where it says to measure the pump connector's purple wires because that is the temp sensor. Are you sure? I thought that is the field control for the pump motor. Those wires internally are connected to some circuits which include coils; I did not see any temp sensor inside the motor. I don't actually know where the temp sensor is...now that I think about it.

Anyway, I'll give those measurements a go and report back.
 

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You cannot rely 100% on wire color codes even looking at V.W wiring diagrams. I showed a photo of the 4 pin motor power connector. If 2 pins are motor power what do you think the other two are? I also showed a diagram of 'Connector A' fitted to the roof controller? So if you weren't happy at the pump end you can pick up the same connections on this connector. MY07 EOS may use different colors to yours. But if you understand what you are doing and measure resistance like I said, you wouldn't get anywhere near the 1000 ohms I said for a temperature sensor by measuring a motor field winding. The motor d.c power connects to a series field and armature which is what you would expect for a high torque pump motor. But if you think there's some kind of electronic speed or torque control on purple wires, I'm not sure what makes you think that?

Its pretty logical to work the pump out. There are 3 pairs of thinish wires for each solenoid which is 6, 2 really thick wires for motor d.c power because you should know it takes over 20Amps, and then 2 skimpy wires that can only be the over temperature sensor. As to where they fitted it or where it is, my 2007 pump is pristine and hasn't gone faulty so that's for you to measure first and find, but don't expect a V.W replacement part for it.

All the information you should need is there, but you have to read and understand it. I cannot find your fault for you. At this level of fault finding you should also have a workshop manual and be looking at the wiring diagrams. If you had started with those, it would have answered many of your questions. You haven't got out the starting grid yet because it gets a lot harder once you get into the roof control and its many sensors. I included information on wiring between the roof pump and the roof controller connectors. Why? Because once you test at the pump you can repeat at the roof controller plug and should get very similar results, albeit the very low pump motor resistance will increase a little due to the length of wiring. P.S just because a motor like this 'spins' doesn't always mean it will do the same under a high torque load. But you say you have 3 motors and they shouldn't all be bad?

I wrote up a comprehensive method to do simple static tests on a roof pump. I concede some of it came from my head, but there are insulation checks deliberately included to find out if the motor internals are dry or water has caused insulation short circuit faults. There shouldn't be any significant insulation breakdown to the motor casing. I haven't checked my pump as installed, but I suspected the hydraulic lines were steel braided and the whole pump body could be chassis ground when they are connected.

So, lets take the scenario of your pump motor or internals being short circuit to the pump frame. You put the motor on a battery and it spins so you think its o.k. Replace it, connect the hydraulics and the motor power is now short circuited and you can't figure it out because it ran o.k on a battery. I'm not saying that's your problem, just showing when you think something is o.k it can be faulty. Included in the price of a reconditioned roof pump is the testing they do before shipping it.
 
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