2004 Allroad BHW Conversion

The fuel pump I got from frans for my conversion also had that extra line you circled in red.
The main difference I noticed from the old gas pump to the new one was that the diesel pump had a metal mesh strainer instead of the foam strainer on the bottom of the gas pump.

interesting on the fuel pumps...I started off thinking the B7 will be a nightmare and actually fried one tandem pump (I think) by using the 6bar standard fuel feed for the 2.0T gasser...

since then I've managed to really clean it out and simplify it - took the fuel filter out (6bar fpr is integrated in the filter) and just run the fuel supply into a manual FPR that bypasses right back to the tank using all stock lines...the car runs like a charm...

the only thing I haven't sorted out is that 1/4 tank cut out - MJ - what do you recon does that? I haven't tested it yet with the simplified system but it consistently did it before that - left me stranded twice actually...I also had really stong vacuum forming up in the tank - it took force to remove the tank cap to refill...all of this should be gone now - just waiting on two fuel fittings to finish it off and post some pics...

Don't know why you are having issues on low fuel.

As stated before all I did to mine was put a "T" in the line. Stock gas pump, installed new fuel filter in the back and on the engine and no FPR.

Currently the fuel gauge is almost on the last bar in the red area (empty!) and it is still running fine. Your words echo in my head though waiting at any minute for it to stop, LOL.

I think its just not enough return flow to power the suction-jet pump to balance the tank. Mine is particularly odd in that round town it will run down to almost nothing just fine, but on the motorway its pot luck whether it will work or not. I can't work out what driving style causes it either - cruising or or foot to the floor appears to have no effect.

I think the gas pump with T is the best idea since there should be plenty of return flow in all conditions then, but mine is off the road and going back to stock so I won't have an opportunity to try it.

Thanks for the fuel pump info guys. I'm going to go the T route for now, sounds like I'd be asking for trouble the other route. I'll keep an eye on the fuel temps, maybe I can add an inline cooler.

I was able to hybridize the left side Allroad intercooler mount with the
Passat intercooler mount and it just barely fits. The Allroad intercoolers are smaller than the Passat one, so it is a bit of a puzzle to get it to fit using the stock piping. Even the Passat ducting will fit, although I may have to trim it to fit the bumper cover.







The entire car has gotten lots of TLC and is pretty much back together. Some new suspension bits, new brakes on all corners and some new tires as well as painting and fluid filming as I go. I just need to find a replacement rear level sensor and it will be back on its wheels.

I received my ECU back from Ottostadt in Ottawa who is a Malone Dealer. I will still need to do some logging for the tune, but I should be able to get the car fully functional.

I punched a hole in the oil pan and added a oil level sensor. Since the 2.7T had one, there would be dash lights with out it. I may have been able to code it out, but figured why not, all the holes are in the casting of the pan. I'll need to run two wires up the the plenum connectors as the BHW ECU doesn't have the provision for it.

A little clean up to do, but everything should look factory by the end.



Just some repinning to do and then cross my fingers.

Very nice.

I was able to mate the original Allroad fuel lines and the TDI lines with tee connectors, pretty ugly but it will work for now.



I checked the fuel pressure right after the tee (dead headed the tandem pump supply line), it peaked at 20psi. I would expect this will drop when fuel circulates through the tandem pump as well. Seems like this will be the easiest solution for the time being, thanks for the tips guys!



Repinning the harness tonight, unfortunately I might have to splice some wires as 2 of the 5 plenum connectors have different styles of pins. I think this was changed in '03 Allroads, as the earlier ones seem to have the same connectors.

Love this thread and hats off to you on figuring all this out! Looking forward to seeing the completed project!

That T looks strangely familiar! LOL

well done Luke - looks great!

I think my fuel issues are different than yours - the B7 is returnless so there's only 1 line going forward and the pressure is sorted out in the fuel filter at the back of the car - anyways I redesigned my sistem and cleaned it all up so will have to see if the 1/4 tank issue is resolved...

when are you coming over for an Ottawa TDi swap meet? the new Holsets are arriving next week...32psi before Christmas or bust! I've got your name on one of those

Well, the Allroad officially has a heartbeat.

I had to make some wiring adjustments as the ECU wasn't getting power, fired right up after that and then wouldn't shut off when the key was removed....woops. Got the meter out and found then was able to find some keyed power to switch to, all was good after that.

Thanks to vwztips and wing_man for the help along the way.

I ran a few wires to the ECU and was able to get the oil level sensor working, one less dash light...

Currently building a stainless exhaust, then I just need to put the bumper cover back on and I should be good to drive.

There are still a bunch of codes I'll have to take care of, 2 for the intake flapper because the previous owner cut the wiring out of the harness for some reason...

The others are:
Channel 3 ABS:
-01044 Control Module Incorrectly Coded
I'm hoping this can be fixed with a reflash, my guess is the auto->manual coding

Channel 1 Engine:
-18034 Powertrain Data Bus (Missing message from TCU)
Hoping a reflash will fix.

-18044 Powertrain Data Bus (Missing message from airbag controller)
Might be wiring? I'll have to investigate.

-17909 Fuel Pump Relay (Open or short to ground)
Might be wiring? I'll have to investigate.

-19456 Glow Plug Indicator Light (Malfunction message from ins. cluster)
Not sure if this is related to using the ESP light, anyone else has this issue?

In the home stretch now!

I had my tune and manual conversion done by Mike at TDTuning. Yes the ABS light will not go out until you recode after the tune and remove the TCU.

Had the same air bag message and Mike had to tweak the program.

Glow plug is because you don't have the correct IC. I got one from Europe off Ebay. Has the GP and the correct RPM range on it. Since mine is on an A6 without air suspension, not sure if my IC shows the height icon on the display or not.

Also, check to make sure your AC compressor comes on. If not you will need to hook up correct Pin # for the BHW ECU to provide an RPM signal.

Powertrain data bus missing message is because of the change of ECU. There's something in the canbus config which needs coding to match them up, but my Audi dealer doesn't even know how to do this. I've seen a couple of A6s showing this message which have had warranty ECUs and even with the dealer computer auto-adapting everything this still doesn't go away.

If you find a solution that would be quite interesting, but it doesn't appear to have an adverse effect on anything. I had missing messages from the airbag and ESP controllers, but the ESP still worked fine. Luckily I never tested the airbags! I've just ignored it since it doesn't cause a CEL.

Thanks for the heads up guys. Hopefully Malone can adjust some stuff.

The Allroad started out as a manual, so it wouldn't have had a TCU. I guess it's the BHW ecu looking for it?

I'll have another look at your AC notes vwztips, it would be great to get my AC working before the snow flies. My system is empty right now but maybe I can jump the pressure switch and see if the compressor will kick in.

Got started on my stainless exhaust last night. I really need a hoist...

I was hoping to get away with straight pipe from the cat back, but it seems pretty loud. Seeing as I'll be doing 140kms a day on the highway, I'm going to try a pair of vibrant bottle resonators right before the exhaust tips. Hopefully that will take the edge/drone off.

I used the stock A6 exhaust on mine and used a Y to go from the single BHW to the dual A6. Just took it to a good muffler shop and they had it done in no time.

I would have preferred to keep the stock Allroad system, however it was completely rotten and expensive to replace. The vibrant resonators are $50 a piece and I had the stainless kicking around, so it was an easy choice.

I ran the wires to/from the ECU for the cruise switch and the A/C RPM signal, I still have to vacuum and fill the AC before I'll know if it works though.

Hoping I'll take it out for its maiden voyage this weekend.

Finished up the exhaust using a couple Vibrant 1790 bottle resonators. I was pretty happy with it, it looks like the original Allroad system from behind. Hard to say how loud it actually is in the garage though, I'll find out soon enough if it's tolerable.



The latest discovery was that my radio no longer works. Can't imagine it's anything to do with the swap though. Radio powers up as normal, should play but there is no sound. Same thing happens if I put a CD in. Anyone have any ideas?

I'm getting 00858: Connection; Radio IF Output to Antenna Amplifier: Open Circuit

Check all your fuses? Isn't there an amp in the back?

Luke I'm doing the same swap. Where did you get the RPM signal from for the A/C control unit?

STP, vwztips helped me out with the RPM signal, however I haven't tested it yet.

I had to run a new wire from pin 28/94 on the BHW ECU to pin 2 on T10P (black connector Allroad). I was able to move an unused wire from the BHW ECU for the purpose, something to do with the auto trans if I recall correctly.



I went for my first drive last night, I'll call it a success. Definitely something up with my brakes, I have to pump 2-3 times before I get firm brakes. They bled fine and doesn't appear to be any leaks. I think I might need a check valve or something inline, I had to run my own tubing for the vacuum system as the line was missing from my parts car.

The bigger issue is the codes I'm getting, the ones that are causing a CEL are:

-17909 Fuel Pump Relay (J17) open or short to ground
-17075 Fan 1 Control Circuit short to ground
-19456 Glow Plug Indicator Light (K29) Malfunction message from Ins Clus.

My ABS light is on and my e-brake light is flashing as well, ABS codes are:
-01044 Control Module Incorrectly Coded
-18034 Powertrain Data Bus - Missing message from TCU

So... I'm hoping Malone will be able to take care of some of these, I know this swap has been done successfully without dash lights on. The CEL is the priority as I won't be able to get an emissions test with it on.

More headaches....

No progress made with my fuel pump relay code. I was using a meter to check voltage and continuity on the low current control side of the relay. The black wire is 12v+ when the key is turned on, the red/blue wire grounds for a second once the ECU is powered up to prime the pump then is discontinuous until the engine is running. This all makes sense to me....

The resistance through the unplugged fuel pump is around 10 ohms, but it's an electric motor so I would expect some continuity.

I'm kind of stumped on this one. Hoping Malone can do something about it in the coding.

Next issue is that I failed to realize the reverse switch wiring was part of the engine harness. So now I have to add a connector and run wires to the plenum connectors. Other swappers take note, as this would have been much easier before the transmission was buried!

Problem I'm having is that the Bentley Allroad diagrams only reference 1 black/blue wire, in reality there are in fact 2 in the plenum connectors. One of them is 12V+ with the key on, originally to power the injectors. No idea what the other is.

The BHW diagrams show a black/blue wire for the MAF, but it says it's only for manual cars. This wire does exist in the BHW harness, which was obviously only sold as automatic. So anyone know the purpose of this wire?

If it's not needed, then I can use the black/blue wire to power my reverse switch as it's supposed to be.

Any advise or thoughts would be appreciated! I'm pretty stumped with this stuff.

The reverse light switch is often hidden in the lighting or basic equipment section of the diagrams so it can be tricky to track down. I think it comes from the shifter on autos so there may not be anything in the plenum for it (presuming the allroad was an auto - can't remember?).

The fuel pump relay on gas models is the glow plug relay on diesel models. Have you taken that in to account? I had to add an extra relay for the fuel pump in my A6, and changed the one in the electronics box to be the glow plugs.

Apologies if this has been covered before - just bashing out some thoughts while I have a mo

Nice build I should have done the allroad
I'm working on 06 a4 putting avf 1.9 in it want to order a harness from Europe but nobody seems to know what harness I need and if it would be a plug and play with my b7 I can't even get wiring diagrams or I would attempt my own harness
Info is hard to come by

I am only showing the White/Blue on the Brown t10d-3 BHW connector as going to the instrument cluster. The Audi side should be the same pin position on Brown t10o-3 so no issue there.

The Blue/White on the BHW t15s-10 is for pre-heat glow plugs for the coolant. That was only for manuals. There is nothing on the Audi for this either. It does nothing.

If you look at the file I sent you, I moved the fuel pump red/blue wire (position t10e-3)on the BHW harness to the Audi harness black plug position t10p-8. I have had no issues or codes.

For the reverse on the automatic cars, there are 2 plugs at the transmission. You need the D shaped plug which goes to the multifunction switch. Cut the wires going to pins 7 and 8. They will go to the reverse plug on the transmission. It doesn't matter which wire goes to which pin on the plug.

Your ABS codes will have to be programmed out with the 5 speed conversion. Again I used Mike at TDTuning and had no issues.

Glow plug error is probably due to your IC does not support this function. I ordered an IC from from a 2003 off of ebay in England. It also got my tach working via Can-Bus as my 2000 A6 did not use CAN-Bus for the tach function.

Vwztips, I started with a manual Allroad so the reverse wiring does in fact go through the plenum connectors. I jumped the pins and the lights came on, so no issues other than the pain of running the wiring.

I kind of did the opposite with the fuel pump wiring, I moved the fuel pump wire from t10p-8 to position t10e-3 on the Audi side to match the BHW harness. Same wires connected though, so I'm very stumped as to why I'm getting the code.

Your spread sheet and the BHW wiring diagram show the black/blue wire that goes to the MAF is only needed for manual cars, this wire does exist in the BHW harness though (which was automatic). Not sure why an auto wouldn't need 12V+ to the MAF? I'm guessing you didn't use it?

Apparently the ESP light can be programmed to work as the glow plug light, if not I'll have to get a different cluster.

Many thanks for your help!

Sorry, I thought you said blue/white. Correct, in this case there is nothing the Black/Blue is used for in this application.

My car was a manual car too. IIRC I added 2 wires through the rubber boot and pinned into one of the connectors. Don't recall which one and I don't have it marked other than t3s3-1 on the BHW side but the 2004 Audi plug is different so not sure which pin you would use.

I want this car. I have an Allroad but I hate the 2.7t, I just went for it and am dealing with the compromise. It sucks. I may have missed it, what did you do for engine mounts?

Also, what did you pay for the tranny? Nice job so far, everything looks very well done. And when I did my C4 S6 swap, the "H" in the fuel lines was the solution I used as well. It worked perfectly.

I have a 2005 and 2001 AR.iBoth with 2.7t. The 2005 I am driving daily. The 2001 is awaiting the drive train from my converted 2000 A6 TDI 6MQ. In the meantime I really like the 2.7 with the power and smoothness. Not so much the MPG when I have been accustomed to going 2 plus weeks between fill ups, with my 2004 Passat TDI with 5 speed manual.