ECU compatibility

[5ktq]

So my car is an '02 with a 8E0 909 518 F ECU

I've been told that the later 8E0 909 518 AF/AK won't work, car won't even start. Does anyone know why? Is the wiring different? Is some CAN module (eg. cluster) different? I find it hard to believe that a car with the same chassis / engine has changed so much that it can't be made to work.

I understand software being incompatible if the ECU HW has changed internally, that makes sense. But the car side I'm not so sure about.

[blitz2190]

no ecu will work unless you have the immo defeated or paired correctly.

Edit, after looking it "should" work but there are changes to the fueling maps on newer ECU's. I have not done this so I'm not saying it defiantly will work.

[5ktq]

Yeah I know that, i'm disregarding immo for this. Everyone says I need an F, but why? What has changed on the chassis between the ECU revisions?

[MoparFreak69]

The F ecu has a different processor speed than the later ones. You can run the later ecu on your car I believe, but not a different file on your ecu.

[diagnosticator]

The "F" ECU was used on '02 manual trans 1,8Ts only. The "AF", "AK" and "BC" ECUs can be used on Manual trans and tiptronic trans cars differing only by a soft coding change. I don't know of any reason the '03> AF, AK and BC ECUs can't be used on an '02. AF, AK and BC ECUs work on all '03> 1,8Ts. I am going to buy a BC ECU because I believe the software calibration is better than the earlier ECUs. All the later ECU will work with the immo active, at least on '03>. I could be mistaken about '02s, there are some unique differences between '02s and '03s>, that may cause an incompatibility. You won't hurt anything by trying an '03> ECU with immo OFF, in an '02. I have studied the wiring diagrams extensively before, and there is no unique wiring diagrams for the '02 vs the '03s> they all use the same diagrams.

[seanf86]

The "F" ECU was used on '02 manual trans 1,8Ts only. The "AF", "AK" and "BC" ECUs can be used on Manual trans and tiptronic trans cars differing only by a soft coding change. I don't know of any reason the '03> AF, AK and BC ECUs can't be used on an '02. AF, AK and BC ECUs work on all '03> 1,8Ts. I am going to buy a BC ECU because I believe the software calibration is better than the earlier ECUs. All the later ECU will work with the immo active, at least on '03>. I could be mistaken about '02s, there are some unique differences between '02s and '03s>, that may cause an incompatibility. You won't hurt anything by trying an '03> ECU with immo OFF, in an '02. I have studied the wiring diagrams extensively before, and there is no unique wiring diagrams for the '02 vs the '03s> they all use the same diagrams.

I have 2 2002's one 5spd m/t quattro and one tip quattro, both have F ecus in them, I think F was just a 2002 only for all 1.8t thing

[5ktq]

I think autos ( not tip ) got the G ecu, which is software compatible with the F. As far as my research goes anyway.

There's so many more of the later ECU's out there, I figured it would be better / cheaper to play with if it is indeed possible.

[rocket1420]

Do you need an '02 ecu to play with?

[jesse500]

From what I've gathered (FWIW) A 518 F ECU can only accept a 518F tune file (stock upgraded, etc...) and can be used in any 1.8T B6, as long as its IMMO defeated.

Otherwise, an IMMO defeated 518 AF/AK/BC tuned (any) will work in any B6 1.8T, and can use BC, AK or AF tune file, doesnt matter.

[EuroxS4]

From what I've gathered (FWIW) A 518 F ECU can only accept a 518F tune file (stock upgraded, etc...) and can be used in any 1.8T B6, as long as its IMMO defeated.

Otherwise, an IMMO defeated 518 AF/AK/BC tuned (any) will work in any B6 1.8T, and can use BC, AK or AF tune file, doesnt matter.

F ecu cannot be used in 2003- and up b6 a4's.It will not work wether it has immo defeat or not.Ecu itself has a different clock speed and cpu.It can only be used on 2002 a4's.This ecu cannot be flashed with different software either it is specific to this ecu and the rom image if different than the af,ak and the bc.2003-2005 af,bc can all be swapped out.However note that if a car that had a bc ecu installed gets a af or an ak cruise control will not work in 6th gear.Also the car will pretty much freak out as af and ak ecus have 5 speed software installed.It is possible to flash a af,to a BC software without issues.2002 Fbox ecu is the ugly bastard child thats up to no good and cannot be interchanged with any other ecu.The AK ecu was only 2003 from what I remember cannot be flashed to a AF or a BC IIRC.The Gbox ecu you have is for a CVT.

The issue with the Fbox ecu is that most cars from 03 and up had various versions of instrument clusters installed.Most are incompatible with a Fbox ecu due to cpu clock speed and so on.Some may be but its a gamble.IIRC 2002 had japanese clusters installed.They sucked big time and were horrible to work on if you had to be any sort of work on the pcb or calibrations for a rebuild or repair.

[EuroxS4]

The "F" ECU was used on '02 manual trans 1,8Ts only. The "AF", "AK" and "BC" ECUs can be used on Manual trans and tiptronic trans cars differing only by a soft coding change. I don't know of any reason the '03> AF, AK and BC ECUs can't be used on an '02. AF, AK and BC ECUs work on all '03> 1,8Ts. I am going to buy a BC ECU because I believe the software calibration is better than the earlier ECUs. All the later ECU will work with the immo active, at least on '03>. I could be mistaken about '02s, there are some unique differences between '02s and '03s>, that may cause an incompatibility. You won't hurt anything by trying an '03> ECU with immo OFF, in an '02. I have studied the wiring diagrams extensively before, and there is no unique wiring diagrams for the '02 vs the '03s> they all use the same diagrams.

No need to buy a BC ecu.There was a TSB from audi in regards to cold start misfires.I believe the SVM code they used updated ak ecu to BC software.Those can be crossflashed without issues.The F cannot.


ecu.jpg

[rfelker]

I have a 2002 5 speed. so are you guys saying that I need to purchase a 2002 cluster to work in my car. I have a bad gas gauge that I want fixed. Don't want to go out and get a newer model year 2003-2005 and it not work. Also Ive been researching custom tunes on nefmoto and wanted to purchase another ecu. Just so I can play and learn tuning. I will have to stick with 2002 tunes correct. If I flash a tune for testing from a 2003 up will brick the ecu?

[EuroxS4]

I have a 2002 5 speed. so are you guys saying that I need to purchase a 2002 cluster to work in my car. I have a bad gas gauge that I want fixed. Don't want to go out and get a newer model year 2003-2005 and it not work. Also Ive been researching custom tunes on nefmoto and wanted to purchase another ecu. Just so I can play and learn tuning. I will have to stick with 2002 tunes correct. If I flash a tune for testing from a 2003 up will brick the ecu?

Yes it will.As I mentioned the layout of the rom image is totally different because 2002 ecus have a different cpu and clock speed.Very easy way to brick the ecu.I believe the cluster you need has a K on the end of the part number and is a japanese cluster much different from the later bosch crypto rb4 clusters.

[diagnosticator]

While the '02 F ECU has a different clock speed than the later ECUs I don't believe that has any particular effect on compatibility. The instrument cluster does not know or care what the ECU clock speed is. There is nothing regarding the ECU internal clock speed that has any external compatibility dependency. The ECU communicates with the IC via CAN buss and the CAN runs at 500 baud between the ECU and the IC, that is the same CAN speed that all B6 power train CAN busses run.

I have never seen a Japanese IC, they are all Bosch. There is no '02 only IC in the parts lists, only different part numbers are listed for different PR numbers.

[seanf86]

Next 03-05 b6 I find at the wrecking yard I'll buy it and swap it out just to see what happens then, unless anyone had an ecu they want to donate for cost of shipping

[5ktq]

Good info, thanks everyone!

My 02 has an rb4 cluster, fwiw

[diagnosticator]

F ecu cannot be used in 2003- and up b6 a4's.It will not work wether it has immo defeat or not.Ecu itself has a different clock speed and cpu.It can only be used on 2002 a4's.This ecu cannot be flashed with different software either it is specific to this ecu and the rom image if different than the af,ak and the bc.2003-2005 af,bc can all be swapped out.However note that if a car that had a bc ecu installed gets a af or an ak cruise control will not work in 6th gear.Also the car will pretty much freak out as af and ak ecus have 5 speed software installed.It is possible to flash a af,to a BC software without issues.2002 Fbox ecu is the ugly bastard child thats up to no good and cannot be interchanged with any other ecu.The AK ecu was only 2003 from what I remember cannot be flashed to a AF or a BC IIRC.The Gbox ecu you have is for a CVT.

The issue with the Fbox ecu is that most cars from 03 and up had various versions of instrument clusters installed.Most are incompatible with a Fbox ecu due to cpu clock speed and so on.Some may be but its a gamble.IIRC 2002 had japanese clusters installed.They sucked big time and were horrible to work on if you had to be any sort of work on the pcb or calibrations for a rebuild or repair.

AF and AK ECUs are compatible with 6 speed MTs also. The soft coding must be set to manual trans, I do know some guys swapping from tip to manual have trouble sometimes with the cruise control not working in 6th gear, but the cause of that is the soft coding of the ECU, the ECU does not know or care what gear is engaged in the manual trans, there is no mechanism in the manual trans to inform the ECU what gear is currently engaged. I don't remember off hand how the cruise control not working in 6th gear is fixed but I believe it has to do with the soft coding of the ECU since the ECU handles all cruise functions internally. The ECU only responds to the clutch pedal switch and retards ignition timing a little when the clutch is disengaged during gear shifts. Ignition timing is readvanced when the clutch is reengaged.
AF was '03 and AK '04, but AK is backward compatible with '03>, also BC from '05. Compatibility back to '02 is the unproven application.

[naysay15]

My 02 has a RB4 cluster just like everyone else's. It has "bosch" and "made in spain" plastered every where. No jap writing to be found anywhere👍👍👍

[rfelker]

I read somewhere someone switched out a 04-05 cluster out of a s4 into a 2002 and it worked. I might be wrong though.

[naysay15]

That would be mr.cschuster. search under his name and u shall find.

[rfelker]

Naysay your right sir.
http://www.audizine.com/forum/showth...002-B6-A4-1-8T

[MoparFreak69]

Diagnosticator;
You are correct that the different clock speed only affects internal ecu functions. Everything external is exactly the same.
If you want to go even further, ALL ME7.5 ecus are physically capable of running the 1.8t in the A4 as the pinout is identical across all of them. The only issue you will run into is non-B6 me7.5 ecus do not have the components on-board to control the FCM, causing random fan operation.
As far as the ecu knowing what gear you are in, there are maps in the bin telling the ecu what rpm range a gear corresponds to vs wheel speed. It just looks at wheel speed and engine speed and sees which map it falls into. Some ecus throw a fit that "5th" gear in the map is too far out of range when you're really in 6th. You can easily adjust the map range a little bit if the issue crops up. I didn't have any problems with my AF ecu after my 0A3 6 speed swap.

[5ktq]

Hmm interesting. So perhaps a GTI or Passat ecu could be made to work if you had to (no heated thermostat or possibly vvt though)

[Kevin C]

Diagnosticator;
You are correct that the different clock speed only affects internal ecu functions. Everything external is exactly the same.
If you want to go even further, ALL ME7.5 ecus are physically capable of running the 1.8t in the A4 as the pinout is identical across all of them. The only issue you will run into is non-B6 me7.5 ecus do not have the components on-board to control the FCM, causing random fan operation.
As far as the ecu knowing what gear you are in, there are maps in the bin telling the ecu what rpm range a gear corresponds to vs wheel speed. It just looks at wheel speed and engine speed and sees which map it falls into. Some ecus throw a fit that "5th" gear in the map is too far out of range when you're really in 6th. You can easily adjust the map range a little bit if the issue crops up. I didn't have any problems with my AF ecu after my 0A3 6 speed swap.

Good info, to add to that:

My understanding is that the difference of when one six speed swap had cruise in sixth and others don't are based on the final drive ratio. The 0A3 has a final drive of 3.02 (FVD version with a 3.89 ring and pinion; The HLD 0A3 has a final drive of 3.19.) , the five speed had a final drive of 3.458 My assumption is that those final drives are close enough to the five speed that the ECU thinks your in fifth (this if for 2003 and prior ECU's). On my 2003 six speed swap using a 02X GJW transmission, the final ratio is 2.815, that's far enough off that cruise wont work in sixth.

Its on my to do list.

[MoparFreak69]

Hmm interesting. So perhaps a GTI or Passat ecu could be made to work if you had to (no heated thermostat or possibly vvt though)

You would lose the MAP controlled thermostat going with a GTI ecu but VVT can be retained. My 01 Gti with an AWW engine has vvt. Anything 01 and newer will take care of that on the VW side. Not sure when the Audi engines started using it.

[Kevin C]

While the '02 F ECU has a different clock speed than the later ECUs I don't believe that has any particular effect on compatibility. The instrument cluster does not know or care what the ECU clock speed is. There is nothing regarding the ECU internal clock speed that has any external compatibility dependency. The ECU communicates with the IC via CAN buss and the CAN runs at 500 baud between the ECU and the IC, that is the same CAN speed that all B6 power train CAN busses run.

I have never seen a Japanese IC, they are all Bosch. There is no '02 only IC in the parts lists, only different part numbers are listed for different PR numbers.

The one I looked at for the years in question all had the same country of origin and appear to be made at the same plant. Perhaps the actual change was the supplier of the display (the little LCD)? Not sure.

I also took a look at Car-Part.com. They don't seem to show much interchange between years. However when you take the part numbers from the clusters and google them, it shows that many of them interchange.

The only other possibility would be different commands to the ECU that are not supported between years. I don't think this is a problem. I am curious to see if the options on the readout varied between years. My 2003 does not have mile traveled on short trips. I get short trip fuel economy and how long I have been driving, but not how far I went. I know that the dealer replaced the cluster... Not clue on the part number.

PN pulled from a 2002 cluster: 8E0920950H

Jim Ellis Auto shows that PN fitting 2002-2005

8E0920950P is for the 2004-2005, Wolf Auto shows it fitting from 2002-2005.

It would be interesting to find out what changed on the newer versions.

http://www.wolfautoparts.com/instrum...0p-132480.html

[old guy]

My 2003 does not have mile traveled on short trips. I get short trip fuel economy and how long I have been driving, but not how far I went.

Same thing for my 2003. And it is definately the original cluster since I am the original owner. If I want to know the miles driven I have to reset the trip odometer with each short trip.

[Kevin C]

Same thing for my 2003. And it is definately the original cluster since I am the original owner. If I want to know the miles driven I have to reset the trip odometer with each short trip.

My 2000 Passat had that feature, on the Audi,I keep scrolling but I never find it :)

[diagnosticator]

The one I looked at for the years in question all had the same country of origin and appear to be made at the same plant. Perhaps the actual change was the supplier of the display (the little LCD)? Not sure.

I also took a look at Car-Part.com. They don't seem to show much interchange between years. However when you take the part numbers from the clusters and google them, it shows that many of them interchange.

The only other possibility would be different commands to the ECU that are not supported between years. I don't think this is a problem. I am curious to see if the options on the readout varied between years. My 2003 does not have mile traveled on short trips. I get short trip fuel economy and how long I have been driving, but not how far I went. I know that the dealer replaced the cluster... Not clue on the part number.

PN pulled from a 2002 cluster: 8E0920950H

Jim Ellis Auto shows that PN fitting 2002-2005

8E0920950P is for the 2004-2005, Wolf Auto shows it fitting from 2002-2005.

It would be interesting to find out what changed on the newer versions.

http://www.wolfautoparts.com/instrum...0p-132480.html

Are you guys saying you don't have a trip odometer selection? AFAIK, the trip odo needs to be reset for each trip, I don't know how it could work otherwise. There is no separate trip odo in the DIS only shows on the main odo, with the trip reset button on the IC.
The dealer installed a 950P IC in my '03 for a warranty replacement. I would like to know the version differences too. Most cases the different part number suffixes operate the same and the version suffixes are changed for other reasons. Other than that, there are different part numbers for fuel type, number of cylinders and clusters with color displays etc.

[jesse500]

F ecu cannot be used in 2003- and up b6 a4's.It will not work wether it has immo defeat or not.Ecu itself has a different clock speed and cpu.It can only be used on 2002 a4's.This ecu cannot be flashed with different software either it is specific to this ecu and the rom image if different than the af,ak and the bc.2003-2005 af,bc can all be swapped out.However note that if a car that had a bc ecu installed gets a af or an ak cruise control will not work in 6th gear.Also the car will pretty much freak out as af and ak ecus have 5 speed software installed.It is possible to flash a af,to a BC software without issues.2002 Fbox ecu is the ugly bastard child thats up to no good and cannot be interchanged with any other ecu.The AK ecu was only 2003 from what I remember cannot be flashed to a AF or a BC IIRC.The Gbox ecu you have is for a CVT.

The issue with the Fbox ecu is that most cars from 03 and up had various versions of instrument clusters installed.Most are incompatible with a Fbox ecu due to cpu clock speed and so on.Some may be but its a gamble.IIRC 2002 had japanese clusters installed.They sucked big time and were horrible to work on if you had to be any sort of work on the pcb or calibrations for a rebuild or repair.

most 2004's & 5's I fiddle with are 518AK's, and 03's seem to be AF. an AK tune file will also flash a AF/BC/AK ECU.

[diagnosticator]

Diagnosticator;
You are correct that the different clock speed only affects internal ecu functions. Everything external is exactly the same.
If you want to go even further, ALL ME7.5 ecus are physically capable of running the 1.8t in the A4 as the pinout is identical across all of them. The only issue you will run into is non-B6 me7.5 ecus do not have the components on-board to control the FCM, causing random fan operation.
As far as the ecu knowing what gear you are in, there are maps in the bin telling the ecu what rpm range a gear corresponds to vs wheel speed. It just looks at wheel speed and engine speed and sees which map it falls into. Some ecus throw a fit that "5th" gear in the map is too far out of range when you're really in 6th. You can easily adjust the map range a little bit if the issue crops up. I didn't have any problems with my AF ecu after my 0A3 6 speed swap.

I know you are knowledgeable about this, but I don't understand how an engine rpm vs road speed map could accurately determine gear position. What happens when the trans is in neutral? What about shifting from neutral to ? gear up or down? What about when the trans is in gear, but the clutch is disengaged? It is much easier for Audi to use a gear position switch on the transmission if the ECU needed to know what gear is engaged. Why would the ECU need that information anyway?

[diagnosticator]

You would lose the MAP controlled thermostat going with a GTI ecu but VVT can be retained. My 01 Gti with an AWW engine has vvt. Anything 01 and newer will take care of that on the VW side. Not sure when the Audi engines started using it.

Background note: Audi originally designed and installed the 5 valve heads, and was the first manufacturer to use a turbo 1.8 liter. VW started using the 1.8T after Audi. The first 1.8Ts where not VVT.

[diagnosticator]

most 2004's & 5's i fiddle with are 518ak's, and 03's seem to be af. An ak tune file will also flash a af/bc/ak ecu.

'03/af '04/ak '05/bc

[old guy]

Are you guys saying you don't have a trip odometer selection? AFAIK, the trip odo needs to be reset for each trip, I don't know how it could work otherwise. There is no separate trip odo in the DIS only shows on the main odo, with the trip reset button on the IC.

Yep. You have to manually reset it. My '97 Passat VR6 did have a separate trip odo in the display that you could toggle through. It automatically reset to "0" after the car had been off for a period of time. I don't recall the time interval but I'm sure it wasn't any longer than 2 hours. If I had to guess I would say it was after 1 hour. There was also a trip odo along with the main odo just as in the B6.

[Kevin C]

Yep. You have to manually reset it. My '97 Passat VR6 did have a separate trip odo in the display that you could toggle through. It automatically reset to "0" after the car had been off for a period of time. I don't recall the time interval but I'm sure it wasn't any longer than 2 hours. If I had to guess I would say it was after 1 hour. There was also a trip odo along with the main odo just as in the B6.

That is what I keep looking for :) I was hoping it was an option on one version.

[MoparFreak69]

The only reason for it is for cruise control. Typical german engineers overanalyze everything. They want to control all aspects of how the engine deals with speed control to make it as smooth as possible. The cruise can somewhat predict the exact amount of load necessary to maintain speed smoothly, without overshooting power requirements.

[Kevin C]

The only reason for it is for cruise control. Typical German engineers over-analyze everything. They want to control all aspects of how the engine deals with speed control to make it as smooth as possible. The cruise can somewhat predict the exact amount of load necessary to maintain speed smoothly, without overshooting power requirements.

It also keeps the throttle from being applied if the transmission is not in gear. Without it, you could slip the transmission in neutral (or try to engage the system in neutral) and the cruise would increase the engines RPM expecting to be able to maintain the vehicles speed. If the engines speed VS MPH is off, then the system does wont activate or shuts off. The system knows if you pressed the clutch, but has no feedback on where the shifter is.

Without it, one could image the cruise control increasing the RPM to whatever level ( red line?) trying to speed up a car that's not in gear.

[jesse500]

'03/af '04/ak '05/bc

I have an 05 usp with an AK ECU in it

[seanf86]

Bringing this back up, found a 03 AF ECU today from a 1.8t tip quattro car, popped it into my wifes 02 B6 1.8t quattro tip car with a 518F, pulled the pins, swapped ecus car fired right up and no lights or codes.

[MoparFreak69]

Bringing this back up, found a 03 AF ECU today from a 1.8t tip quattro car, popped it into my wifes 02 B6 1.8t quattro tip car with a 518F, pulled the pins, swapped ecus car fired right up and no lights or codes.

Thanks for updating and confirming my thoughts about interchangeability!