# J49 fuelpump shortcircuit on a W12 SWB 2004 in Sweden.



## aswede (Apr 15, 2009)

The engine lamp lit last summer. The Vokswagen dealer never found the fault. But it went away. 
This summer it started again same fault codes. And the fuse blew. Changed and it blew again. The garage cannot find whats wrong. They have had a look at it a couple of times but not figured it out. The annoying yellow light is still on but the engine runs fine.
Anyone else who has experienced these fault codes? 
Any input would be appreciated.


Address 01: Engine Labels: Redir Fail!
Controller: 07C 906 018 Q
Component: D1-6.0L-AT A ª5639
Coding: 0000173
Shop #: WSC 70599
4 Faults Found:
18335 - Relay for Aux Coolant Pump (J496): Open Circuit
P1927 - 004 - No Signal/Communication
19468 - Relay for Fuel Pump 2 (J49): Open or Short to Ground
P3012 - 004 - No Signal/Communication
17841 - Secondary Air Pump Relay (J299): Open Circuit
P1433 - 004 - No Signal/Communication
18331 - Please Check DTC Memory of ECU Number 2
P1923 - 008 - Implausible Signal
Readiness: 0110 1101


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## WillemBal (Nov 20, 2010)

aswede said:


> The engine lamp lit last summer. The Vokswagen dealer never found the fault. But it went away. This summer it started again same fault codes. And the fuse blew. Changed and it blew again. The garage cannot find whats wrong.


Hi Jan,
It is quite unlikely that all faulty components as listed in the VCDS scan are gone at the same time. I suspect a common cause. These components are all powered, relayed or wired through the electronics box which is located in the right air intake plenum chamber.
It is possible that this box was opened once, perhaps long ago, and then not properly shut and sealed. VW even once released a service bulletin emphasizing the importance of properly sealing up the cover after opening.
It is in this particular box where fuse *SD6* (10 Amps) can be found. It gives power to all listed components (including the secondary air pump). Therefore it is pretty sure that there is something wrong with the power supply to these components, even though your dealer replaced “a fuse”. It not necessarily needs to be a fuse which is blown. Due to water ingress in this particular box, which is obviously an important component which needs to be sealed at all times, corrosion of wires, fuse holders, relays and wiring may have occurred, as a result of repeated exposure to water, eventually leading to one or more failures.

There is a very informative thread which you might want to read. Even though you may not yet have experienced any water ingress in the right footwell of the cabin, the thread gives much information about what the water ingress in the box itself can do to your car, how to solve problems caused by it and what you can do to prevent it.


*Water Leakage into Cabin by way of Electrical Box*

You might want to ask your dealer to check this box and its seal. If you do so, then also let him inspect the installed electrical components for traces of water damage, in particular the contacts lips and wires of fuse SD6.

Willem


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## Paximus (Aug 26, 2011)

Isn't this forum great, when you see such calm and helpful advice [Willem's post].

Sorry, nothing to do with the thread, I just felt the need to say that. :beer:

Cheers,
Chris


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## perfrej (Dec 24, 2009)

*Diagram... PanEuropean?*

Jan, you forgot to mention that in your specific case, the wiring diagram that VW (Din Bil) has does not agree with what's actually in the vehicle. Maybe we should have Michael PanEuropean extract the schematics that he believes should be for your car? We could compare them to the ones that Din Bil has and see where the hickup is...

Apart from that, I agree that water ingress may certainly be the case. Heck, I had water ingress right next to that place in the adaptive cruise control thingy and had to clean contacts and what have you.

Michael? Can you pull a schematic for a specific VIN with the tools that you have at your disposal?

/per


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## WillemBal (Nov 20, 2010)

Paximus said:


> Isn't this forum great, when you see such calm and helpful advice [Willem's post].


Just trying to avoid panic...


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## WillemBal (Nov 20, 2010)

perfrej said:


> Jan, you forgot to mention that in your specific case, the wiring diagram that VW (Din Bil) has does not agree with what's actually in the vehicle.


It may be hard to find one schematic or document which exactly matches with what is present in the car. I think that Jan also forgot to mention some other specific details which might be helpful with the troubleshooting. For instance, the thread's title suggest that there was a short circuit in the fuel pump. Was this the actual diagnosis of the dealer and if so, on what was this diagnosis based?
And which fuse did they replace? Did it blow again after replacing? At which stage was the diagnose made? After clearing the DTC's, was the scan still showing the same faults? How can it run fine without such a vital component as the fuel pump (relay). So perhaps the scan doesn't represent the actual status?

Willem


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## PanEuropean (Nov 3, 2001)

perfrej said:


> Can you pull a schematic for a specific VIN with the tools that you have at your disposal?


Hi Per:

Not really... this because VW doesn't correlate wiring diagrams to VINs. In practice, there are very few changes to the wiring design during the manufacturing lifetime of the car, and when a change is made, it will be clearly noted on the wiring diagram (in other words, the wiring diagram will show two possible variations).

Normally, revisions to wiring design are only made at model year changes, and if the change is significant, a new (different) wiring diagram will be published.

-------------------

I have not been following this discussion closely - that due to a huge amount of travel I have done this week - but after taking a close look at the fault codes published in the first post, I'm kind of perplexed, because it appears that the vehicle has numerous faults that are not related to one another. For example:

*18335 - Relay for Aux Coolant Pump (J496): Open Circuit* - this is an 'after-run' coolant pump that is used to circulate coolant after the engine has been shut down, in order to effect even cooling of the engine (in other words, to prevent hot-spots from developing). It may also have a role to play in the "Residual Heat" comfort function, and perhaps (I'm guessing here) even in circulating coolant if a Webasto parking heater is installed. But... it has nothing to do with fuel delivery.

*19468 - Relay for Fuel Pump 2 (J49): Open or Short to Ground* This one should be very easy to troubleshoot - the component is reporting an open circuit condition. This relay is located in position 6B within the relay panel directly above the left battery. The relay itself is probably a 'generic' relay - in other words, not some exotic Phaeton-only part. I've posted an illustration below that shows where it is. If the relay itself is the same part number as the relays in positions 5A and 5B (there is a good chance that they are all the same PN), then simply changing positions of the relays will enable a fault in the relay itself to be confirmed or ruled out.

It's noteworthy that this relay is in the trunk of the car. That rules out water infiltration as a possible cause of any problems with this relay.

*17841 - Secondary Air Pump Relay (J299): Open Circuit* This relay is in the electrical box that is located in the cabin air intake plenum, under the windshield on the right hand side of the car. If the relay box is opened to investigate this relay, great care must be taken to properly seal up the relay box - that process (and the potential disasters that can arise from not sealing up the box properly) is well documented elsewhere. Note, though, that again, there is no connection of any kind between this system and the fuel delivery system. The secondary air pumps blow additional combustion air into the exhaust system following a cold start to bring the catalytic converters up to operating temperature as quickly as possible. This is an emission control system. Arguably, a fault here will not affect drivability, but it will trigger the Check Engine Light (MIL).

*18331 - Please Check DTC Memory of ECU Number 2* - This one is almost 'boilerplate' - one ECU can only handle a maximum of 8 cylinders, and this engine has 12. So, there are two ECUs, one for each side of the engine. If a problem is reported by the 'slave' ECU (controller 11) that monitors the right side of the engine (cylinders 7 through 12, also referred to as banks 3 and 4), the fault will be recorded by the second ECU (controller 11), not by the first ECU (controller 01). All this message means is "Go look and see what controller 11 is complaining about". Once the faults are cleared from controller 11, this message will disappear from controller 01.

Hope this information helps.

Michael


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## PanEuropean (Nov 3, 2001)

WillemBal said:


> How can it run fine without such a vital component as the fuel pump (relay).


There are two fuel pumps in the Phaeton, one in each lower lobe of the tank. I don't know if they have individual relays - I would presume so, but I have not investigated this.

Michael


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## aswede (Apr 15, 2009)

*It did resolve.*

The car spent 4 days at the garage, it was taken apart but they couldnt find the problem. There seems to be something strange about the wiring that doesn't match the diagram????
Well the engine lamp is not lit anymore but this might happen again.
The car runs fine but has been hard to start at some instances but then it is just to push the gaspedal and it starts. It was the second time it did. First summer 2010 then this summer again. I did not have to pay anything.

Merrry Christmas from warm Stockholm, but I head to the Maldives tomorrow for a cruise on 
the atollexplorer.com


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## PanEuropean (Nov 3, 2001)

aswede said:


> ...I head to the Maldives tomorrow for a cruise on the atollexplorer.com...


Per:

Sorry I couldn't help you get the fuel pump on your Phaeton fixed, but I can assure you that when you arrive in the Maldives, the fuel pump on this plane will be working just fine... the photo below shows me fixing it shortly after I put this newly-manufactured aircraft into service in the Maldives earlier this year (I work for the company that manufactures the aircraft). 

Michael

*Fuel Pump Service...*


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## PhaetonMike (Jul 17, 2017)

*How did it turn out?*

Was the car fixed?




aswede said:


> The car spent 4 days at the garage, it was taken apart but they couldnt find the problem. There seems to be something strange about the wiring that doesn't match the diagram????
> Well the engine lamp is not lit anymore but this might happen again.
> The car runs fine but has been hard to start at some instances but then it is just to push the gaspedal and it starts. It was the second time it did. First summer 2010 then this summer again. I did not have to pay anything.
> 
> ...


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