B5 2.7T to B6 A4 Wiring guide

[blitz2190]

Sounds great, I'll add it all to the first post

[Waspjr]

Online.

It was too simplified... made me nervous. I'm happy with the Alldata website.

Lol never even thought to use alldata duh headbang

[gottaBdope]

Okay, this wiring is fcking me up. I have alldata diagrams for both cars, I've read every thread on here about the wiring for this swap, and I've matched up as much as I can find. I already did the body plugs (mostly based on the OP) and I get a no start. I don't hear the fuel pump prime and I don't get any attempt to a turn over. I feel like it has something to do with immo or starter relay, maybe even clutch sensor. It's been so long since I started my car that I can't remember if the "depress clutch" message goes away when you have it depressed.

I have a fairly detailed chart on excel for what I did. Does any one have the time or desire to help me out and take a look at it? I'm not asking for anyone to do this for me, but I could certainly use a second set of eyes. If you can, shoot me a pm with your email and I'll send over the excel sheet. Thanks in advance :-D

[Shhmaudi]

Posting to find my way back someday :)

[Waspjr]

Gottab check for power at your starter. Also use a set of jumper cables and put both thepositive and negative junper cabkes on the negative battery terminal and the other r d one on the engine and one on the body.

[diagnosticator]

I don't understand #3 a) "Side note also need to jump this to the coolant fan relay to turn on when a/c is on so it actually blows cold air." Why? The rad fan does not operate according the the A/C status, that is the job of the A/C condenser cooling fan. (the right side fan facing forward from the driver's seat)
The B6 rad fan and the A/C condenser cooling fan function totally independently from the other. The A/C condenser cooling fan is controlled by the A/C controller in the cabin via the fan controller module, and runs whenever the A/C compressor is active. The rad fan, runs when commanded by the ECU via the rad fan controller, and has no function associated with the A/C compressor operation. This is also why using a 3.0l A/C compressor for the swap, is necessary, since the compressor is a variable displacement compressor, and is controlled by the HVAC control module. Using a 2.7T A/C compressor requires unnecessary modifications to the wiring with a configuration not used in any car from the factory and the compressor cannot be controlled properly by the HVAC controller used in the B6.

[blitz2190]

I don't understand #3 a) "Side note also need to jump this to the coolant fan relay to turn on when a/c is on so it actually blows cold air." Why? The rad fan does not operate according the the A/C status, that is the job of the A/C condenser cooling fan. (the right side fan facing forward from the driver's seat)
The B6 rad fan and the A/C condenser cooling fan function totally independently from the other. The A/C condenser cooling fan is controlled by the A/C controller in the cabin via the fan controller module, and runs whenever the A/C compressor is active. The rad fan, runs when commanded by the ECU via the rad fan controller, and has no function associated with the A/C compressor operation. This is also why using a 3.0l A/C compressor for the swap, is necessary, since the compressor is a variable displacement compressor, and is controlled by the HVAC control module. Using a 2.7T A/C compressor requires unnecessary modifications to the wiring with a configuration not used in any car from the factory and the compressor cannot be controlled properly by the HVAC controller used in the B6.

I meant the aux fan on the condensor, fixed it

[diagnosticator]

I meant the aux fan on the condensor, fixed it

I still don't get why the jumper is needed to run the condenser fan. that fan is controlled by the HVAC controller in the cabin.

[blitz2190]

I was going based on what was found in the 2.7t swap thread to power the fan. I still have not finished my wiring entirely so for now was just doing what others reported as working. I think it could also be triggered by the pressure sensor near the c ondensor, and going based on your comment could you not use the 1.8t as well, I thought they and the 3.0 were the same.

[ColoradoRS4]

I have detailed wiring for a BEL from a 2003 tiptronic A6 into a 2004 AVK 3.0L A4 which I will upload later.

Specifics about my swap:
- I simply re-pinned my engine harness using the existing 2.7t plugs. Because of some of the position changes I needed to splice a different end onto the wire so that it would fit the correct receptacle in the plug (wider vs more narrow)
- My speedometer and tachometer required no additional wires. I don't have a 5k rev cut problem.
- Because I used a tiptronic engine, the harness did not have the plug for the reverse sensor on the transmission so I had to steal it from the existing 3.0L harness and fabriate a sub-harness.
- The engine harness was also lacking the correct A/C compressor wire so I had to run those as well.
- As of right now, the rad fans are not working. I opted to use the original 3.0L fans and control module, but that we before I realized that the A6/2.7t fan module actually controls the auxiliary coolant pump under the intake manifold.
- I'm unsure at this point whether cruise control works or not. There was a single common wire between the two cars, and the A4 uses a "Steering Column Control Module" whereas the A6 has four or so wires running directly between the ECU and the cruise control stalk.

More to come later.

Did you ever have a chance to put your wiring together to share with everyone?

[blitz2190]

updated the wiring, also wired the leak detection pump and will post that when i get a chance to look at the diagrams again.

[diagnosticator]

I'll have to study them more but the reason i asked is it would seem that way was closer the original wiring of the 2.7t as both the 1.8t and 2.7t on that wire ran to the injector harness.
2.7t compressor, and I figured I'd run the same line to a relay to run the fan relay when the a/c is active.One side of the compressor switch to ground 17d/5 to the other side and fan relay

If the 3.0l compressor fits, then you should use that since the 3.0l compressor is a variable displacement unit, controlled by the HVAC controller. If it does not fit, then it's worth the effort to make it fit. The 2.7T compressor is a cycling clutch drive, completely different from the 3.0l compressor. If you use the 2.7T compressor, how are you going to control it? The 3.0l HVAC controller will not control the 2.7T compressor.

[blitz2190]

If the 3.0l compressor fits, then you should use that since the 3.0l compressor is a variable displacement unit, controlled by the HVAC controller. If it does not fit, then it's worth the effort to make it fit. The 2.7T compressor is a cycling clutch drive, completely different from the 3.0l compressor. If you use the 2.7T compressor, how are you going to control it? The 3.0l HVAC controller will not control the 2.7T compressor.

you already asked this, and the main post has been updated the correct way a while ago

I don't understand #3 a) "Side note also need to jump this to the coolant fan relay to turn on when a/c is on so it actually blows cold air." Why? The rad fan does not operate according the the A/C status, that is the job of the A/C condenser cooling fan. (the right side fan facing forward from the driver's seat)
The B6 rad fan and the A/C condenser cooling fan function totally independently from the other. The A/C condenser cooling fan is controlled by the A/C controller in the cabin via the fan controller module, and runs whenever the A/C compressor is active. The rad fan, runs when commanded by the ECU via the rad fan controller, and has no function associated with the A/C compressor operation. This is also why using a 3.0l A/C compressor for the swap, is necessary, since the compressor is a variable displacement compressor, and is controlled by the HVAC control module. Using a 2.7T A/C compressor requires unnecessary modifications to the wiring with a configuration not used in any car from the factory and the compressor cannot be controlled properly by the HVAC controller used in the B6.

[diagnosticator]

I forgot about that post. What post is the main post?

[blitz2190]

I forgot about that post. What post is the main post?

the first one, deleted the one with the question you quoted so I don't confuse anyone. Its refined now to the point that it's as close to oem as I can get it as long as the relays and extra notes I described are followed, and have confirmed working on a 2005 b6 s4 and 2004 b6 a4, and should be helping a friend with a 2003 b6 a4 wiring soon. I'll also be posting my circuit for the a/c and fan module once i refine it to the point of being reliable.

[diagnosticator]

the first one, deleted the one with the question you quoted so I don't confuse anyone. Its refined now to the point that it's as close to oem as I can get it as long as the relays and extra notes I described are followed, and have confirmed working on a 2005 b6 s4 and 2004 b6 a4, and should be helping a friend with a 2003 b6 a4 wiring soon.

The A/C controller already activates the A/C condenser fan, whenever the compressor is active, by sending control commands on the CAN buss to the fan control module. No need for a custom fan trigger sensor.

[blitz2190]

The A/C controller already activates the A/C condenser fan, whenever the compressor is active, by sending control commands on the CAN buss to the fan control module. No need for a custom fan trigger sensor.

there is when that module no longer exist, I made an mechanical setup with a bmw switch, which i found later you can use the stock 2.7t switch. but it triggers the large fan through a relay at 91*c, and the smaller one at 108*c. And right now I'm testing the new schmitt trigger i made to trigger the fan when the condenser switch hits the middle range of pressure. The reason for the mechanical setup is the 2.7 ecu doesn't trigger the fans like the b6 does because it had a clutch fan and only a small aux fan, and I didn't want to mess with any canbus module when a tried and proven mechanical switch is much more reliable. So far it has perform flawlessly I have just under 5K miles on this setup so far in mixed driving, stop and go traffic, and highway and the temp holds perfectly.

[diagnosticator]

there is when that module no longer exist, I made an mechanical setup with a bmw switch, which i found later you can use the stock 2.7t switch. but it triggers the large fan through a relay at 91*c, and the smaller one at 108*c. And right now I'm testing the new schmitt trigger i made to trigger the fan when the condenser switch hits the middle range of pressure. The reason for the mechanical setup is the 2.7 ecu doesn't trigger the fans like the b6 does because it had a clutch fan and only a small aux fan, and I didn't want to mess with any canbus module when a tried and proven mechanical switch is much more reliable. So far it has perform flawlessly I have just under 5K miles on this setup so far in mixed driving, stop and go traffic, and highway and the temp holds perfectly.

What module no longer exists?

[blitz2190]

What module no longer exists?

the fan control module, I replaced it with the dual temp switch and 30 amp relays.

[blitz2190]

Updated main post with b7 abs wiring

[Poopcorn]

I have detailed wiring for a BEL from a 2003 tiptronic A6 into a 2004 AVK 3.0L A4 which I will upload later.

Specifics about my swap:
- I simply re-pinned my engine harness using the existing 2.7t plugs. Because of some of the position changes I needed to splice a different end onto the wire so that it would fit the correct receptacle in the plug (wider vs more narrow)
- My speedometer and tachometer required no additional wires. I don't have a 5k rev cut problem.
- Because I used a tiptronic engine, the harness did not have the plug for the reverse sensor on the transmission so I had to steal it from the existing 3.0L harness and fabriate a sub-harness.
- The engine harness was also lacking the correct A/C compressor wire so I had to run those as well.
- As of right now, the rad fans are not working. I opted to use the original 3.0L fans and control module, but that we before I realized that the A6/2.7t fan module actually controls the auxiliary coolant pump under the intake manifold.
- I'm unsure at this point whether cruise control works or not. There was a single common wire between the two cars, and the A4 uses a "Steering Column Control Module" whereas the A6 has four or so wires running directly between the ECU and the cruise control stalk.

More to come later.

sorry to bring this back... So did you do your wiring yourself?

[blitz2190]

From what I remember looking at the bel diagrams it's not to far off. If you have a diagram it would be easy to find any differences

[nefkntym]

When I did my swap, I had the APB harness and the BEL female plugs. There were a few pins that needed to be moved between the two. There were a few wires that were the same function at the same position in the plugs but the wiring coloring was off as well.

[dougyfresh]

When I did my swap, I had the APB harness and the BEL female plugs. There were a few pins that needed to be moved between the two. There were a few wires that were the same function at the same position in the plugs but the wiring coloring was off as well.

The BEL harness also uses different connectors for various sensors on the engine relative to APB.

Knock sensors are one such sensor that uses a different connector. BEL and 1.8T AMB us the same connector. S4 APB uses a different connector.

Coil packs are also different as the BEL 2.7T uses the same coils from the 1.8T and no separate ICMs. I'm physically swapping the connectors on my APB harness so I can use the 1.8T/BEL coil packs and no ICMs rather than run ICMs with S4 coils. This also requires BEL valve covers. OR you do the spacer mod and run FSI coils (not worth it IMO as I got the same large spark plug gap with 1.8T coils than others with FSI coils).


I'm using a BEL engine (2004 A6) with an APB wiring harness from a 2000 S4. Mainly because my wiring for the B6 chassis was already done on the APB harness before I switched physical engines. To combat the knock sensor issue I just used the knock sensors from my APB engine rather than solder the BEL connectors onto my APB harness (can't repin as the connectors are different sized terminal ends).

[A4SoftWalker]

Think OP fixed the issue recently Doug.

[blitz2190]

The BEL harness also uses different connectors for various sensors on the engine relative to APB.

Knock sensors are one such sensor that uses a different connector. BEL and 1.8T AMB us the same connector. S4 APB uses a different connector.

Coil packs are also different as the BEL 2.7T uses the same coils from the 1.8T and no separate ICMs. I'm physically swapping the connectors on my APB harness so I can use the 1.8T/BEL coil packs and no ICMs rather than run ICMs with S4 coils. This also requires BEL valve covers. OR you do the spacer mod and run FSI coils (not worth it IMO as I got the same large spark plug gap with 1.8T coils than others with FSI coils).


I'm using a BEL engine (2004 A6) with an APB wiring harness from a 2000 S4. Mainly because my wiring for the B6 chassis was already done on the APB harness before I switched physical engines. To combat the knock sensor issue I just used the knock sensors from my APB engine rather than solder the BEL connectors onto my APB harness (can't repin as the connectors are different sized terminal ends).

as julex told me in the b5 section you can also use the rs6 coils that bolt down the same as the apb but use the newer coils without icm's. Also this will transfer heat away from the coil better than with spacers. after buying spacers and fsi coil the cost is about the same.

[nefkntym]

For push down coils, the OE Touareg adapters are less than $5 a piece and you can make the ICM delete adapters with OE parts for less than $20.

[blitz2190]

For push down coils, the OE Touareg adapters are less than $5 a piece and you can make the ICM delete adapters with OE parts for less than $20.

those work but arent they plastic? if the tune compensates for the dwell time the heat thing isn't as much of an issue, but for those of use the with stock dwell the bolt down should disapate more heat. or theres always the aftermarket aluminum spacers.

[nefkntym]

They are plastic. I used the 034 coil adapters when I did the ignition swap. Honestly I never had a problem with heat and I would touch the adapters all the time. In hindsight I would use the Touareg adapters now, they will work just as well as steel, aluminum and delrin. Ultimately, the igniter in the actual coil in encased in plastic anyway and you can buy 22 of the stock adapters for the price of 6 aluminum ones.

[dougyfresh]

as julex told me in the b5 section you can also use the rs6 coils that bolt down the same as the apb but use the newer coils without icm's. Also this will transfer heat away from the coil better than with spacers. after buying spacers and fsi coil the cost is about the same.

In my case I have 8 good working 1.8T coils so instead of spending money on other coils I'm just soldering connectors on my harness to use the coils I already own (and know work very well).

[chris_72]

Lots of great info here! Thanks a lot guys!
I have an 03 1.8t Avant and I just got my hands on a 2001 2.7tt 6-speed as a donor. Can't wait to dig in!

[elewsader]

I've gone through the wiring diagrams for the BEL engine with an auto harness, and for those of you that have successfully completed the BEL swap, would you be able to help confirm that I have these pin outs correct?

I'm also lacking 4, 6, 7, and 9 is questionable since I was unable to identify them anywhere in the Bentley.

Thanks!

---

2003
Pin # BEL Color
1 T10p/Black bl D Ignition Starter Switch
2 T10p/Black gn/bl E87 AC control head
3 T10p/Black ws/gr K3 Oil Pressure Warning Light
4 T10p/Black ro J271 Motronic Engine Control Module Power Supply Relay
5 T10p/Black br/ge 269 Ground
6 T10p/Black EMPTY
7 T10p/Black bl/ge K28 Engine Coolant Level/Temp Warning Light
8 T10p/Black ro/bl G5 Tachometer
9 T10p/Black bl/br G3 Engine Coolant Temperature Gauge
10 T10p/Black br/ro G21 Speedometer

1 T10o/Brown gr/sw A76 Kline
2 T10o/Brown EMPTY
3 T10o/Brown EMPTY
4 T10o/Brown ro/sw B Starter
5 T10o/Brown EMPTY
6 T10o/Brown EMPTY
7 T10o/Brown EMPTY
8 T10o/Brown sw/ro G5 Tachometer
9 T10o/Brown ro/gr K83 Malfunction Indicator Lamp
10 T10o/Brown EMPTY

1 T17k/Red EMPTY
2 T17k/Red sw/ge E87 AC control head
3 T17k/Red sw/gr E87 AC control head
4 T17k/Red EMPTY
5 T17k/Red EMPTY
6 T17k/Red EMPTY
7 T17k/Red EMPTY
8 T17k/Red ws/ge J569 Brake Booster relay
9 T17k/Red EMPTY
10 T17k/Red EMPTY
11 T17k/Red EMPTY
12 T17k/Red EMPTY
13 T17k/Red or/gr A122 Can Bus Low
14 T17k/Red or/sw A121 Can Bus High
15 T17k/Red ro/ge V192 Brake System Vacuum Pump
16 T17k/Red li/bl J234 Airbag Control Module
17 T17k/Red EMPTY

1 T17i/White ge/bl G79 Throttle Position Sensor
2 T17i/White ge/li G79 Throttle Position Sensor
3 T17i/White br/ro G79 Throttle Position Sensor
4 T17i/White gr/ge G185 Sensor 2 for accelerator pedal position
5 T17i/White gr G185 Sensor 2 for accelerator pedal position
6 T17i/White br/gn G185 Sensor 2 for accelerator pedal position
7 T17i/White ro/gr Cruise Control
8 T17i/White bl Cruise Control
9 T17i/White ro/ge Cruise Control
10 T17i/White sw/ws Cruise Control
11 T17i/White ro/sw F Brake Light Switch
12 T17i/White ws/ro F47 Brake Pedal Switch
13 T17i/White EMPTY
14 T17i/White EMPTY
15 T17i/White EMPTY
16 T17i/White ro/gr E87 AC Control Head
17 T17i/White ro S130 Fuse for secondary air pump

1 T10n/Orange ro/gn E87 AC Control Head
2 T10n/Orange EMPTY
3 T10n/Orange ro/ge V51 After-run Coolant Pump
4 T10n/Orange sw/bl
5 T10n/Orange sw/bl N30 Cylinder 1 Fuel Injector
6 T10n/Orange ws/ge
7 T10n/Orange ge/ro
8 T10n/Orange gr/ge
9 T10n/Orange EMPTY F95 After-run Coolant Thermal Switch
10 T10n/Orange EMPTY

[silva]

Hi all,
I just wanted to chime in and let everyone know that I've successfully been able to control the J293 cooling fans using an Arduino board and the original 2.7T coolant fan switch. I'm a noob to programming in general, but I was able to do it, and as such, so can anyone else. Total cost for the board: <$10 for an Arduino Uno.

The fan stays off when the car is first started, and then comes on at low speed when the first of the two stage coolant fan switch is activated. When the second stage is activated, the fan runs at full speed. The speeds can also be adjusted by tweaking one variable in the code.

Also, I've converted my B7 RS4 to ABS 5.7. The wiring schematic posted on the first page is incorrect. There are two wires that are incorrectly identified. Also, if the donor vehicle is a 2002, there are a couple of other differences as well. If the OP contacts me, I can provide the correct wiring schematic.

[Bische]

Hi all,
I just wanted to chime in and let everyone know that I've successfully been able to control the J293 cooling fans using an Arduino board and the original 2.7T coolant fan switch. I'm a noob to programming in general, but I was able to do it, and as such, so can anyone else. Total cost for the board: <$10 for an Arduino Uno.

The fan stays off when the car is first started, and then comes on at low speed when the first of the two stage coolant fan switch is activated. When the second stage is activated, the fan runs at full speed. The speeds can also be adjusted by tweaking one variable in the code.

Also, I've converted my B7 RS4 to ABS 5.7. The wiring schematic posted on the first page is incorrect. There are two wires that are incorrectly identified. Also, if the donor vehicle is a 2002, there are a couple of other differences as well. If the OP contacts me, I can provide the correct wiring schematic.

Did you swap you're B7 RS4 with a 2.7t?

[silva]

Yes, I had a bad cylinder in the 4.2 and those aren't rebuildable so I took it out and put a 2.7T in it.

I posted a pic or two here: http://www.audizine.com/forum/showth...1#post11748641

[MurkyRivers_A4]

This guide was a huge help in getting my swap done. Blitz definitely knows what he's doing and was/is a lifesaver.

Thanks Blitz!

[igz]

Hello, im in the middle of doing the wiring for my swap. this has been really helpfull but im stuck on the additional notes. please help me out :)

[MurkyRivers_A4]

What ECU pin does the clutch switch go to? I have an auto harness and do not have the wire for the clutch switch going to the ECU from the body plug and will need to add it.

"Clutch Vacuum Vent Valve Switch T15(T15e) WHITE Pin13 red/green"

[blitz2190]

Hello, im in the middle of doing the wiring for my swap. this has been really helpfull but im stuck on the additional notes. please help me out :)

saw your pm, I'll take a look tonight.

What ECU pin does the clutch switch go to? I have an auto harness and do not have the wire for the clutch switch going to the ECU from the body plug and will need to add it.

"Clutch Vacuum Vent Valve Switch T15(T15e) WHITE Pin13 red/green"

pin 39 careful when taking apart the ecu plug, it is very easy to pull other wires out. also on the body side the wire is already there, it just went to the shifter, assuming the body is also an auto, if not its already where it needs to be, I'll look tonight to get the correct wire that went to the shifter, I had to do this to mine as the body was an auto.

[MurkyRivers_A4]

pin 39 careful when taking apart the ecu plug, it is very easy to pull other wires out. also on the body side the wire is already there, it just went to the shifter, assuming the body is also an auto, if not its already where it needs to be, I'll look tonight to get the correct wire that went to the shifter, I had to do this to mine as the body was an auto.

Donor body, engine, and harness were all auto. I did add a wire to the body connector to match what your diagram listed (T15e White Pin13 red/green) although the wire I added is black violet, which doesnt matter.

My concern is from the 2.7t harness, basically the receiving side for the T15e White Pin13, having a wire that leads to the ECU for the clutch switch, which I dont think it does. If it does, like you say it does, then I can clip it and splice a new wire and pin it to ECU pin 39.... right?