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Discussion Starter · #1 ·
Ok, I've got a 2.0 2008 Wagon @ 105,000mi and I've been told that I might have to replace the harness in the engine due to 'old brittle' harness.

First off, I looked around and can't seem to find a DIY for this. Troubling and leading into; Second, this sounds like BS.

Thoughts?
 

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I have heard of replacing harnesses or mass bunches of wires on a car from having gangrene (that's were corrosion travels the length of the wire, even through the insulated portion of the wire).
Other than replacing a few wires on some connector end that is exposed to severe heat or the elements that nature dishes out, I've never heard of replacing a complete engine harness.
It's not like our cars are 50 to 60 years old and all crusty.
 

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Discussion Starter · #3 ·
It's not like our cars are 50 to 60 years old and all crusty.
This is the thought I had. I pressed the service adviser about it and he said that they replace a harness in some sort of VW about once a week. That seems crazy. I would suspect if it was some common or even more than rare occurance that it would be somewhere on the forum in the past few years. I found bubkiss.
 

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If it were older and from TX, then I could see it being needed, but most people repair sections of wiring as needed down here (usually coil pack wiring). I think the dealer is looking to buy a boat.
 

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What kind of problems are you having?

Out of all the Passat's I have worked on, I have only seen 1 with an issue having to do with the engine harness.
Where the harness goes through the first part of the firewall and has that rubber boot thingy and then the harness goes directly into the ECU box on the drivers side, the rubber boot thing that makes a seal going through the firewall was not inserted properly and was all folded over on the underside of the harness, that coupled with broken engine mounts that should have been replaced a lifetime ago, there was some minor chaffing going on with the wires.
Other than that, the only real problem I have seen is at the connector for the MAF sensor. Those tend to get brittle and break when the air filter box is taken apart for air cleaner changing.
 

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For me the challenge will be to find the right section!
Having a 1988 Jetta GLI 16V (ugh!) in my possession, I can tell you that finding deteriorated wiring is cake...what isn't cake is replacing wires in any harness individually.

Take a close look at all the wiring plugs in your engine compartment. If any of the plugs have wires that crack when the wire is bent back onto itself (180 degree bend), that wire section needs replacing. Whether you want to replace the entire wire (say from ECU to MAF), will depend on how much super glue (yes VW uses copious amounts in wiring harnesses for anchoring) is in the harness. :banghead: Alternately, you can cut out the four to six inches of wire with brittle (or worse missing) insulation and replace it with a short section of wire with a factory terminal (dealer sells these).

Ultimately, it's probably a good idea to first check all the wiring going to your coil packs as this area is failure prone, even on the previous generation Passat. If you find that 98 percent of the wires in your engine bay are inside a vinyl/plastic covering (i.e. unexposed), then PZ's last sentence holds much water...

If there are connector contact issues with the harness plugs, there are some effective, but costly (Stabilant 22 ;) ) contact enhancers out there that will magically solve any intermittent contact issues. And yeah, I've been acquainted with a few techs who would rather throw a new harness in rather than treat a connector contact issue.
 

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Discussion Starter · #8 ·
Thanks! That's good info. I got "Helga" back from the dealership on Tuesday and so far no CEL. We're going on Vacation for 2 weeks starting Saturday, so I should have plenty of time to contemplate my next move. I doubt I'll have enough time between now and leaving to get into this.

The 6" pigtail you mentioned that I can get from the dealer, is that for any connector on the car?
 

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No, there are different size terminals (nothing generic, believe me) for each harness plug. There are probably one or two common sizes, but it'll take a visit to the dealership parts counter to get the specific wire terminal with ~4 inches of yellow color-insulated wire you're looking for. You'll see a fancy looking retention tang on the back of the terminal end.

When visiting a dealer for instance, you'll tell the VW parts guy/gal that the terminal and wire you're looking for installs into the wiring harness plug that connects to the MAF (if your diagnostics tell you there's a problem with the MAF signal getting to the ECU).
 

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Whether a TDi or tFSI the harness (loom) to the injectors or coil packs are notorious for becoming intermittent.
On both engines the reason is that there's only one, yes, one! earth return. And it's the earth return that becomes intermittent giving intermittent and otherwise non-traceable by static means faults.

Dunno about that dealer changing out one per week, but it is a common issue. It's a common design fault.

The dealer recall on coil packs and injectors often causes the fault to arise coz that loom is disturbed. But because changing the loom isn't in the recall instructions, it doesn't get done until customer complains under dealer service warranty
 

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Discussion Starter · #11 ·
Whether a TDi or tFSI the harness (loom) to the injectors or coil packs are notorious for becoming intermittent.
On both engines the reason is that there's only one, yes, one! earth return. And it's the earth return that becomes intermittent giving intermittent and otherwise non-traceable by static means faults.
So now I go in search of where the ground on the harness is. This will be awesome.:banghead:
 

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Why go searching for anything, besides gasoline, if your engine doesn't exhibit any running problems?

About 30 yrs ago, an elderly German mechanic told me something about German cars..."if something (engine, transmission, etc.) is running OK, leave it the **** alone. German cars will usually give a visible/audible warning before mechanical failure."
 

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Discussion Starter · #13 ·
Well, I do have the CEL on. And under load (weighted down with 2 adults, 3 kids, and camping stuffs in the boot and on the roof) there has been episodes where the engine will hesitate. For example when I'm trying to pass a slow-as-hell trucker on a 2-lane road but can't. It is almost as if, during this situation, the turbo is out to lunch. Park it overnight and she's ready to rumble again.

The underlying thing here, is if I decide to sell, I'm going to need this problem gone. The family is quickly considering a camping that involves a vehicle that can tow. The Passat is not that car.
 

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RE: That CEL. It's probably just one of the oxygen sensors getting tired on a 9 yr old car with >100K on the odo (Emissions warranty on these only goes to 80K). Replaced the oxygen sensor on my '99 Passat around 110K or so.

Try to go by Advance Auto, O'Reillys, Pep Boys, Kragen or other auto parts store in MI to have the CEL code read and determine the cause for that CEL.

Not surprising that a loaded to the hilt B6 Passat 2.0T Tiptronic Wagon would be slow...just think how much slower you'd be if you had 4-Motion. ;) You might've been able to pass that trucker if VW had made (but didn't) a B6 Passat 3.6L V6 MT Wagon.
 

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Discussion Starter · #15 ·
Well I've had it into two shops, including the dealership and the first checked the sensor and thinks it's the ECU. :/

Just a few weeks ago I had these codes:
P0113 Intake Air Temperature Sensor 1 Circuit High Input
P2181 Cooling System Performance (<-- this code appeared twice)

The temp sensor is good, so it's got to be the wiring on that end. But I'm unsure if the wiring issue I'm having would cause the hesitation. Or the turbo cutting out. I'm taking it tomorrow morning to check the CEL again.

As to the 3.6L V6 MT Wagon. I'd give my left nut to swap mine for the R36.
 
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