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Hi,

My drivers power seat adjustments stopped working, and the problem seems to be the power supply to the seat (when using an external power source all adjustments seem to be working).

Where is the power source for the seats?
Does it go through the fuse box?
Are there separate power sources for lumbar support and the other adjustments?

Thanks,

-- Alex
 

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Discussion Starter #2
Hi,

After some research I managed to find the power source to the power seat adjustments:

- all seat adjustments (except lumbar support) seem to be feed by a 20A thermal fuse hidden in the dash, behind the drivers small drawer in the left side (close to but not in the larger fuse board on the left side of the dash). In my case it was a green 20A/12V fuse with reference VW 443 937 105. This location is not documented in most VW workshop manuals.

- lumbar support is feed by a separate fuse, probably in one of the two fuse boards mentioned in VW documentation.

Regards,

-- Alex
 

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Hi Alex and Co.,

My wife and I just purchased our 2008 Eos a couple days ago and were able to negotiate the price down because the passenger power seat wasn't working at all, with the exception of the heated seat feature. I am searching for the location of the fuse for the passenger power seat power supply. Would any of you happen to know if each seat has its own fuse? Or do they share the 20 amp fuse mentioned above?? The driver's power seat is working perfect.

WE LOVE THIS CAR! And are excited to get it into tip-top condition. Thanks for sharing!!!

---Manny
 

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I don't have power seats, only the heated seat pads so any help I offer is from research: :)

You posted a vid. for a seat repair. I think this was for another vehicle (Audi?) and could be misleading because the EOS option has a driver easy entry control unit J572 fitted under the seat frame and the vid. describes a fairly simple non-electronic mechanical manual switch. But it is useful to see how the motor wiring connects:confused:

When you are fault finding complex systems such as this you will find thick and thin wires. Thick wires usually carry high currents e.g to motors and heaters, whilst thin wires are low current attached to sensors or low power switches. Thick wires will often go to an electronic control module and the thin wires give the switch and sensor protection functions. Control modules may contain relays or most often MOS transistors. MOS transistors are easily damaged by over current (e.g short circuit) or voltage faults. Control modules may have embedded CANbus controlers receiving and sending digital commands to other parts of the vehicle system including diagnostics.

The EOS driver seat DOES have a fuse S44 which is under the dash panel mentioned by Alex99. I also discovered there's a sunroof motor fuse there too!. However, these are THERMAL FUSES and you should know that any safety fuse that fails, does so because of a fault and not due to a fuse failure! You don't replace fuses until you have first checked out wiring and motor for short circuits or excess current draw. I can imagine a scenario of a seat motor setting itself on fire inside all that foam and vinyl whilst you are sat on it driving with with the wife and kids and all that acrid black poisonous smoke killing them in a trapped car. :(:(

Be careful what you mess with and what you think you might know about. Thermal fuses are special and available in a wide range of current/time values. If you are an expert at these things you may be able to lift a part ID from the fuse and find a substitute. If you are not an expert buy replacements from the Stealer using the correct part for your VIN.

In addition to thermal fuse S44 which appears to provide all the power, there are LIMIT SWITCHES for upright and recline movement. I guess these will be inside the seat or attached to a moving part. They tell the controller and motor when the ends of the position are reached. I don't know if these limit switches are normally closed and open on limit or are the other way around. A reason for thermal fuse failure is a limit switch fails and the motor or main thermal fuse overheats. :confused:

The passenger seat is simpler but still has a side easy entry control unit J573 and limit switches for upright and recline backrest. It does get its power (30A) from the same positive connection in the wiring harness fed from the thermal fuse under the dash.

The electrical seat wiring and control is complex and it will be difficult to fault find some faults without a wiring diagram. I'll run through some possibilities to try, but remember this is from desk research:

1. A failure of BOTH seats suggests failure of the common thermal fuse in the dash panel.
2. A total failure of one seat but not the other suggests a wiring fault in the common power wire to the thermal fuse. Inside the seat loom on a wire fed from the thermal fuse there should be a common tap or feed point providing power to both seats.
3. If some seat functions on the same seat work (seat heaters excluded) but others don't, then common power must be present and the main thermal fuse is o.k.

I would then start looking at the limit switches, motors and associated wiring because there is one for each recline and upright motor. Of course, if there are individual manual switches that give these functions, they should be checked with a meter. But these switches if using thin wire will only be sending control signals to the seat controllers.

The seat controllers J572 and J573 translate the low power manual seat switches into high power control for the respective motors - rake motor, height motor, backrest motor, or lumbar motor.

The driver seat also has a longitudinal motor and a sender (somewhere along the track?) to sense the seat forward & back position. It appears as though the Easy entry button on the drivers side merely sends a command to the driver seat controller to operate the respective seat motors.

4. The seat controller probably powers each motor. You can confirm this by looking at the wire gauge sizes. Thick wires= common high power or motor, thin wires e.g on switches or buttons = control signals. The video posted may be misleading as it appears to show a high power manual seat switch, whereas I think the EOS routes the high power through seat controller modules J572 & J573 :confused:

5. The seat controllers add other variables. Check all the seat wiring for continuity first on the high power side. I.e all thick wires that disappear into the seat for each motor. If the seat motor wires can be isolated from the controller by disconnecting a connector, test each seat motor individually with an ohm meter or power source, but remove the test power once the motor hits the limit and stalls. I assume these will be reversible d.c motors?

6. If the motors all work, move on to the actual wiring checking wires to the seat controller, all the switches including limit switches if you can find them. Poke a test voltmeter on wiring around the controller and check if it has a 12V power source.

7. Now you are left with the seat controller: Scan for fault codes. The most likely problem inside will be the output motor control devices. They either use relays or high power MOS transistors? With detailed wiring diagrams (and they are complex!!) you can check if there's an ouput motor voltage and it reverses polarity when the switch is operated, if so the control is ok but the wiring to the motor or the motor itself is faulty - but also remember those limit switches!

These are a few (unproven) ideas from my research you can try out, but don't underestimate the complexity of the EOS seat control system where you could eaily get out of your depth with a simple mindset to your problem. I think you would be very lucky to find a one stop solution on the internet. I'm rather glad MY07 EOS dosn't have them. :):)
 

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Thanks so much for the quick and super thorough reply.

After reading through all of your info I think I am going to let the dealership sort out the cause of the problem. I could pull up the drivers and passengers seats and start swapping parts to troubleshoot the issue, but I think that paying the dealership for an hour of time will save me a ton of hassle. I am hoping that a power lead got pulled out or that it is an inexpensive part replacement.

I'm not sure if this would help narrow down the issue, but the lumbar function isn't working either. In one of Alex's previous posts here it sounded like the lumbar function is on a separate fuse and power supply. At what point do all of these components begin to share electronics and switches? Could it be the entire switching mechanism? Because that seems unlikely. Or is there a module that the lumbar and seat movement share??

Many thanks again for all of your experienced guidance!
 

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With these complex systems you cannot assume somebody elses problem and solution is the same as yours. From what desk research I've done for you, the power source is common. But once you introduce electronic control, it only needs one of those thin control wires to the controller to go bad (or the controller) and the symptom of no power will be the same. That is why you take a logical approach to testing. V.W technicians do the same thing using their 'guided fault finding' flow charts. What I posted for you isn't far off the same kind of thing, but mine hasn't been tested so may have errors or omissions. But if you were starting as a DIY, something gifted with caveats is better than nothing. :)

Even with my simple seats I thought V.W hadn't really thought out how to get wiring from the movable seat squabs to a fixed location on the floor without wires flexing. :( When you get your car back (and you have more wiring) have a good look underneath and see if you can do anything to the routing to reduce wire flexing. V.W design their wire types and sizes by computer mostly for current capacity, but here were there is frequent movement they should have used higher gauge multi stranded or braided wires. This is particularly important with their driver easy entry system because the seat and its wiring will be moving back and forth a lot.

The lumbar support adjustments and the motor are fed from fuse 34 in the fuse box on the end of the dash and don't appear to be using the controller, just manual power switches and you should be able to test for 12 volts there. V.W fuses can vary in their locations. My advice is to take a good photo of your fuse box first, then starting at the top left, remove each fuse one at a time and test its continuity. Best to do it that way because you cannot always see the wire is broken. On your seat, the lumber power wire to the switch panel should be red with a black stripe, but no guarantees as I never trust V.W wiring colors between different VINs! There's a brown wire on the same panel that might also be power? :confused:
.
 

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Voxmagna thanks again for the informative reply.

I ended up getting the car to the dealership for an hour of diagnostic time. Turns out there was some evidence of water getting into the connectors under the seat. The good news is that all the switches and motors work (bottom / back / lumbar / top side switches).

They figured out that the seat is not getting power. Somewhere there is a broken lead or something is not as it should be. They wanted another $290 to continue diagnosing the issue and I can't afford that right now ( the car also needs new tires, new front control arm bushings, a new gas door release button, and a new oil pan). So eventually I'm going to try and track down the issue by following the power leads back into the dash.

Would anyone have the wiring diagrams available to download? These would be a lifesaver while doing this troubleshooting!

As always, any help is greatly appreciated! :)
 

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On my volkswagen eos I had heated seats with electric lumbar support and now I have heated seats with electric lumbar support and electric movement.
I connected to them the power that was missing for the electrical adjustments by taking energy from the cable that feeds the lumbar support.
But the easy entry function does not work and there are these two orange 6-7 cables not connected. Could anyone help me connect them?
 

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The best answer is to get hold of the official wiring diagram. You can get access through erwin.vw.com or try to find a copy of ElsaWin, or hope that someone on here can get you a wiring diagram.

One thing to note is that the easy entry needs a control module like this - is that part of the seats that you installed?
 

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Pin 6 (orange/green) is the convenience CAN bus high connection; pin 7 (orange/brown) is the convenience CAN bus low connection. That would explain why the easy entry doesn't work: the convenience system will tell the easy entry function to only work when the door is open.

Chances are the wiring won't be there for that, so you'll need to run some 0.35mm2 twisted-pair wire back to the CAN gateway, which if you have a left-hand-drive Eos is located under the steering wheel.
 

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I returned to the demolition center where I took the seats and studied the wiring and the two orange cables reach a pin under the steering wheel. in the picture. But is the right seat connected to the same connector? I couldn't check.
Now my question is what right must be connected to the same connector under the steering wheel? After connecting the cables do I need to do a coding with the vag?
 

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You need to connect the convenience high and low cables to the corresponding connectors dewcribed here. This is how to get to the gateway.

I don't know if it'll need coding - it's possible that it may need adding to the gateway. VCDS or OBDeleven can do that.
 

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The best answer is to get hold of the official wiring diagram. You can get access through erwin.vw.com or try to find a copy of ElsaWin, or hope that someone on here can get you a wiring diagram.

One thing to note is that the easy entry needs a control module like this - is that part of the seats that you installed?
Correct! I gave some answers in my post #8 whilst looking at a V.W wiring diagram. But I know that V.W can change their wiring colors and plenty of checks have to be done at either end of a wire to confirm it is what you think and has some resemblance to the wiring diagram. Note I said 'resemblance' because you shouldn't make assumptions, even with an erwin diagram.

You cannot expect answers to connect this color wire to that when so many wiring V.W variants and options exist. The seat wiring with all its functions is pretty complex to figure out. That's where the skills of an automotive electrician come in. They have experience to work with partial or suspect information.

Using the wiring information It should be possible to test each of the seat functions using wiring test patches, a power source, no switches and without the extra layer of the controller and its Canbus. If the seat functions all work, then fault finding moves to the controller, its compatibility in your car and adaptation coding.:confused:
 

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yes to my seat everything works. only the easy entry function does not work because those 2 orange cables are not colored now I will find the black sub-sub wiring as shown in the picture and if the two orange cables will also be missing I will just connect them and it should work. But I wanted to know if the right passenger seat is also connected there
 

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O.K, so it sounds like you are left with a control function to sort out? Orange wires and with some color of stripe are often used as Canbus control wires. At this level, you need to get yourself a copy of ElsaWin by fair means or foul. As I said before, the wiring for these seats is quite complex and you need wiring diagrams as long as you understand they don't always tie up exactly. IMHO I wouldn't experiment with Canbus connections because being a comms bus, there will be other vehicle functions using it and wiring polarity is important.
 

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I wanted to know if the right passenger seat is also connected there
Yes, the passenger seat needs the same connection for the CAN-bus wiring.

The information I wrote in the post is from the official wiring diagram, so you should be OK to follow that. The wiring in your original photos did seem to have colours - look closely and you can see that one of them is orange and brown. Orange and brown is always the CAN low connection.
 

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ok so my photos are correct? the left and right seat cables reach that black connector under the steering wheel. I just have to check and disassemble my car for the hp connection, but I still need to get there.
 

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Hi,

After some research I managed to find the power source to the power seat adjustments:

- all seat adjustments (except lumbar support) seem to be feed by a 20A thermal fuse hidden in the dash, behind the drivers small drawer in the left side (close to but not in the larger fuse board on the left side of the dash). In my case it was a green 20A/12V fuse with reference VW 443 937 105. This location is not documented in most VW workshop manuals.

- lumbar support is feed by a separate fuse, probably in one of the two fuse boards mentioned in VW documentation.

Regards,

-- Alex
Hi Alex I’ve having the same problem, I did replace the switch, I checked the fuses on the left side of the car and under the hood, can’t find the thermal fuse mention, is there another set of fuses under the dash, any pics to help? Thanks in advance. DK
 
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